Category Archives: Various

US TEO Power Suppy: you want to get killed by a USB charger?

This is one of the worst electronic gadgets that my workshop has every seen, a US TEO Brand A5951 USB charger. Usually, not much can go wrong with the design of a 5 V switchmode power supply, but with this device, all went wrong, a combination of bad design, bad manufacturing, and non-existing sense for product responsibility.

Can you see the wires – right hand side is low voltage side, left hand side is mains! Can you see the solder stuck to the board – almost connecting mains and low voltage?

The only “safety” function I can see if a PCB trace fuse (left hand side zig-zag) on a mildly flammable paper board.

Even the case isn’t sealed – the manufacturer is even saving the glue!

That’s the brand name and numbers, if you have one of these, take it out of service immediately!

Seems Canada has some clever authorities – they found a whole lot of unsafe USB chargers. Remember the good old days when it was illegal to import just any kind of crap?

AB Arboga Maskiner U2508: a simple DRO (linear glass scale readout)

Recently, I have moved a U2508 milling/drilling machine to my Ludwigshafen workshop (from the remote workshop, where there is more space for heavy machinery). It’s a really good machine, slim, but very well built and useful for all kinds of drilling and milling work. It has an automatic feed in in one direction, and the dials are usually quite accurate.

Still, it will be a great advantage of time saving and some accuracy improvement to add a linear scale, at least in the manually-moving direction, so I can mill shoulders and similar features to a very high level of precision and repeatability.

Also the quill will get an electronic readout – but this will be covered later.

Luckily, I had a simple readout around, dating back to 2007, based on an ATmega8515, with some logic, and MAX7219 display drivers.

The case was made from melamine composite boards, these are oil and grease resistant – excellent for workshop use.

Here, the schematic of the input section. The sampling frequency of the counter is about 62.5 kHz, so the TTL signals from the glass scale first pass through a ~160 kHz low pass filter, and are then squared up by Schmitt triggers, 74LS14.

The main processor is running at 16 MHz, and very few extra parts are needed to drive the LED 7-segment displays, using two MAX7219 in chain configuration. The LED segment displays are much preferred for workshop and DRO use, because speed and clarity is everything for this application, and nothing can really replace the good old LED 7-segment displays here.

The power section, note that the regulator will need a heatsink of about 10~15 K/W capacity
– the unit is drawing up to 0.5 Amps at 5 Volts.

The input section…

The drivers…

The wiring, all quickly soldered together with some copper wire.

The code – it uses a gray code approach with continuous sampling of the A/B inputs. This approach is easily coded, and has very deterministic timing, and noise immunity. Any errors found (like, if both lines change state within on sampling cycle) will be indicated by a red LED.

dro_simple1

Now, I only need to mount the glass scale (found one that fits in may parts collection…), and replace the “minus” LED (a 3 mm LED) with a minus bar-shaped LED, just for the better looks.

Note that the software has provisions for a matrix key-pad, but for the present application, the “zero” buttons are all that is needed.

Length Endcoder Interface: reading the Heidenhain

This little post may help those that are dealing with rotating or linear encoders, and have been wondering how to build a circuit that actually works, and with a degree of reliability useful for industrial applications. Around machine tools, and similar equipment that rely on such encoders, there is a lot of electric (and audible!) noise, so most hobby circuits that just take some TTL signals and do some quick stuff and calculations won’t work. Let’s try with a real circuit and some good code.

Here is the device, it’s a Heidenhain ST1278, 10x interpolated TTL output micrometer.

According to the datasheet, it has a 20 micron grating, which will lead to a 2 micron signal period, allowing us to get 0.5 micron resolution.

After carefully opening the plug, which has the Heidenhain logo, and secret Heidenhain electronics inside, I can tell you, Heidenhain uses a 75ALS194 line driver, to drive the RS422 output.

We will be using a DS26C32ATM line receiver, to get the differential signal converted back to TTL level.

The differential lines is terminated in 120 Ohms (watch out for their dissipation, if you consider building this in SMD), and has two 220 pF capacitors to absorb and high frequency noise. This thing is running at 100 kHz max.

The output of the DS26C32 is going right to a ATmega328P, sitting on a Arduino nano clone, for convenience. This uses the common CH340G seriell to USB converter to talk to a host computer.

This is the full board. USB power is enough, even for the Heidenhain, and a HX711, which is also used in this device, for other purposes.

How to get the Heidenhain signals decoded into position. Well, we follow a sampling approach here, rather than using any of the rising edges, triggers, etc. – we just sample the two Heidenhain lines at 125 kHz, and compare the sampling result to the last result (of sample N-1), to determine if the Heidenhain moved forward, backwards, or not at all. If both lines change status -we know that something went wrong (e.g., if Heidenhain is moving to fast, or if some noise comes in despite all the effort to keep the noise controlled by the high current differential line).
The 125 kHz sampling is running on a timer-triggered interrupt routine. The duration of the interrupt can be monitored -at least in debug mode- by watching a test pin of the mega328P, by setting the test pin high when the interrupt is called, and clearing it once the service has been completed.

The initial software still used more then 4 microseconds for the sampling, a bit too much, this can be reduced to 2.4 microseconds, even without any special tricks.

Below, you can see the effect of a sampling error (introduced by very quickly pushing the sensor arm inwards), it takes slightly more time to handle the error.

Finally, all that remains is to communicate with the host – this is done at a data rate of 12 Hz, plenty for this application. The data interval is triggered by the HX711 load cell converter, and the the full dataset, including, current encoder reading, error count, load call reading, and time-stamp are transmitted to the host all in one packed, as hex encoded data, and at 19200 baud. All pretty fail-safe and slow, but working just fine, and still a lot of idle time on the line (see transmission pattern on the scope below)!

Below, the avr-gcc code performing all these wonderful tasks.

hhenc hx711 _180128.c

Manuals Additions: Motorola!

Thanks to a kind contributor, Mike, about 230 Motorola manuals have found there way into to archive. Included are various detail manuals and service guides of the GP series, and other quite popular Motorola radios.

Happy to receive any of your manual collections related to test equipment, high frequency electronics, or related fields. Will keep them online free of charge for everyone, and all well backed up.

motorola
| |– [8.7M]  6864115B18-D GP300 Basic Service Manual.pdf
| |– [421K]  AP-73 user manual.pdf
| |– [2.4M]  Astro Digital Spectra _ Digital Spectra Plus Basic service manual.pdf
| |– [3.3M]  ASTRO Saber Basic Service manual DigitalPort.pdf
| |– [1.6M]  Astro service software user guide.pdf
| |– [7.5M]  Astro XTL5000 basic service manual.pdf
| |– [1.9M]  Astro XTL5000 Detailed User Guide.pdf
| |– [7.9M]  ASTRO® XTSâ„¢ 2500 user guide.pdf
| |– [897K]  BPR_40.pdf
| |– [7.0M]  Business Portable Radio service manual.pdf
| |– [363K]  Business Portable Radio user guide.pdf
| |– [1.8M]  CDM and PRO SERIES detailed service manual.pdf
| |– [2.5M]  CDM Series Basic Service Manual.pdf
| |– [8.4M]  CDM Series Control Station Service and Installation Manual.pdf
| |– [2.3M]  CEP400 basic user guide.pdf
| |– [6.2M]  CM140 basic user guide.pdf
| |– [1.3M]  CM140 CM160 service manual.pdf
| |– [491K]  CM160 user guide.pdf
| |– [3.8M]  CM200 CM300 PM400 basic service manual.pdf
| |– [8.7M]  cm200 cm300 pm400 detailed service manual.pdf
| |– [351K]  CM340 user guide.pdf
| |– [523K]  CM360 User Guide.pdf
| |– [2.3M]  CM Radios Detailled service manuals.pdf
| |– [1.3M]  Commercial Series CM service information.pdf
| |– [160K]  CP140_160.pdf
| |– [8.4M]  cp150 cp200 detailed service manual.pdf
| |– [5.5M]  CP185 Service Manual.pdf
| |– [8.4M]  CP200 Detailed service Manual.pdf
| |– [7.0M]  Digital XTS 3000TM full featured model user_s guide.pdf
| |– [5.3M]  Digital XTS 3000 user guide.pdf
| |– [8.1M]  disney2wayadv user manual.pdf
| |– [3.9M]  DM 3400 user guide.pdf
| |– [1.1M]  DM4400 user guide.pdf
| |– [1.2M]  DM4600 user guide.pdf
| |– [7.2M]  DP 3400 user guide.pdf
| |– [8.4M]  DR 3000 basic service manual.pdf
| |– [8.4M]  DR3000 MOTOTRBO Repeater basic manual.pdf
| |– [6.9M]  DR3000 MOTOTRBO Repeater basic service manual.pdf
| |– [9.0M]  DR3000.pdf
| |– [ 79K]  Emergency Foot Switch instruction manual.pdf
| |– [5.2M]  EP450 basic service manual.pdf
| |– [1.5M]  EP450 detailled service manual.pdf
| |– [ 63K]  Flashing Adapter HLN9742 Service Manual.pdf
| |– [345K]  FLASHport user guide.pdf
| |– [4.0K]  GM1200E detailled service manual
| | |– [1.6M]  dsm_a3s.pdf
| | |– [249K]  dsm_a4s.pdf
| | `– [924K]  GM1200E_SM _EN.pdf
| |– [924K]  GM1200E service manual.pdf
| |– [326K]  GM1200_UG_EN.pdf
| |– [889K]  GM1280 user manual.pdf
| |– [1.4M]  GM300 basic service manual.pdf
| |– [808K]  GM300 service manual (3 parts).pdf
| |– [ 14M]  GM300 service manual.pdf
| |– [217K]  GM340 user guide.pdf
| |– [4.0K]  GM350 installation manual
| | |– [440K]  350IN_EN.pdf
| | |– [ 25K]  350RS_EN.pdf
| | |– [ 74K]  350ug_en.pdf
| | `– [119K]  950rmkit.pdf
| |– [561K]  GM360 user guide.pdf
| |– [692K]  GM380 user guide.pdf
| |– [722K]  GM-660_Manual.pdf
| |– [871K]  GM series Radio Installation manual _ service manual.pdf
| |– [119K]  GM Series service information.pdf
| |– [3.3M]  GP1280 basic service manual.pdf
| |– [1.9M]  GP1280 user guide.pdf
| |– [4.0M]  GP300 Basic service manual.pdf
| |– [231K]  GP300 Service manual (schematics).pdf
| |– [1.9M]  GP320 user guide.pdf
| |– [8.4M]  GP328 GP338 Detailed service manual.pdf
| |– [8.1M]  GP328 Plus detailed service manual.pdf
| |– [453K]  GP328plus GP338plus GP338XLS Basic service manual.pdf
| |– [8.1M]  GP328plus GP338plus GP338XLS detailed service manual.pdf
| |– [4.1M]  GP330 user guide.pdf
| |– [1.9M]  GP340 Ex Portable Radio basic user guide.pdf
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| |– [257K]  GP344 user guide.pdf
| |– [3.4M]  GP350 service manual.pdf
| |– [4.0K]  GP350 User Guide
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| |– [1.8M]  GP360 user guide.pdf
| |– [2.8M]  GP380 Ex Portable Radio basic user guide.pdf
| |– [1.9M]  GP-380_Manual.pdf
| |– [1.2M]  GP388 user guide.pdf
| |– [4.4M]  GP580 Ex Portable Radio basic user guide.pdf
| |– [4.0M]  GP600 series Basic Service manual.pdf
| |– [2.2M]  GP640 GP680 Basic Service manual.pdf
| |– [1.8M]  GP640 GP680 Basic User Service manual.pdf
| |– [2.2M]  GP-680_Manual.pdf
| |– [1.3M]  GP68 User Guide.pdf
| |– [4.0K]  GP Series detailed service manual
| | |– [384K]  B32E_Sect1_Service Maint.pdf
| | |– [518K]  B32E_Sect2_Keypad_A3.pdf
| | |– [ 89K]  B32E_Sect2_Keypad_A4.pdf
| | |– [576K]  B32E_Sect3_Controller_A3.pdf
| | |– [210K]  B32E_Sect3_Controller_A4.pdf
| | |– [2.6M]  B32E_Sect4_VHF_A3.pdf
| | |– [255K]  Chap 1 Introduction_A4_v0.pdf
| | |– [234K]  Chap 2 Theory of Operation_A4_v0.pdf
| | |– [718K]  Chap 3 Maintenance_A4_v0.pdf
| | |– [551K]  Chap 4a Controller and Keyboard Info_A3_v0.pdf
| | |– [240K]  Chap 4a Controller and Keyboard Info_A4_v0.pdf
| | |– [525K]  Chap 4b VHF Info_A3_v0.pdf
| | |– [510K]  Chap 4c UHF1 Info_A3_v0.pdf
| | `– [511K]  Chap 4d UHF2 Info_A3_v0.pdf
| |– [9.3M]  GR300 GR500 service manual.pdf
| |– [2.3M]  GTX LCS 2000 service manual.pdf
| |– [968K]  HF-SSB Automatic Antenna Tuner owner_s manual.pdf
| |– [573K]  HKLN4197A_PRO2150_Eng.pdf
| |– [9.3M]  HT1000 JT1000 MT2000 MTS2000 MTX series Service manual.pdf
| |– [477K]  HT1000 MT2000 MTS2000 MTX series Service manual.pdf
| |– [4.3M]  HT1250 user guide.pdf
| |– [4.9M]  HT750 HT1250 MTX850 MTX1250 MTX8250 MTX9250 basic service manual.pdf
| |– [1.9M]  HT750 HT1250 MTX850 MTX1250 MTX8250 MTX9250 supplement basic service manual.pdf
| |– [ 12M]  HT800 VHF service manual.pdf
| |– [3.0M]  HT90 service manual.pdf
| |– [2.2M]  HT Series detailed service Manual.pdf
| |– [2.2M]  LCS2000 service manual.pdf
| |– [1.4M]  LTS 2000 user_s guide.pdf
| |– [6.9M]  Mag One basic service manual.pdf
| |– [1.7M]  MagOne Basic Service manual.pdf
| |– [433K]  Mag One BPR40 Brochure.pdf
| |– [4.8M]  MagOne detailled service manual.pdf
| |– [2.1M]  MCS 2000 Mobile Radio.pdf
| |– [295K]  MCS 2000 Model I User Guide.pdf
| |– [306K]  MCS 2000 Models II _ III user manual.pdf
| |– [2.1M]  MCS2000 service manual vol-1.pdf
| |– [1.1M]  MCS2000 service manual vol-2.pdf
| |– [1.3M]  MICOM-2E ALE owner_s guide.pdf
| |– [ 36M]  motorola gm 900_sm.pdf
| |– [533K]  MOTOROLA KIT HSN4035 Service Instruction.pdf
| |– [647K]  motorola Models T4800 T4900 Instruction.pdf
| |– [1.2M]  motorola Models T5600 T5620 T5700 T5710 T5720 instruction.pdf
| |– [1.4M]  motorola Models T5800 and T5820 instruction.pdf
| |– [1.0M]  motorola Models T5900 T5920 and T5950 instruction.pdf
| |– [ 38M]  motorola mototrbo dp3400 3401 3600 3601 sm.pdf
| |– [101K]  Motorola NMN6250 NMN6251 – service manual.pdf
| |– [7.0M]  motorola_novacommunications_business_portable_radio_cp125.pdf
| |– [7.0M]  motorola_nova_cp125_sm.pdf
| |– [372K]  Motorola P040 P080 Controller – schematics.pdf
| |– [533K]  Motorola P040 P080 UHF – schematics.pdf
| |– [772K]  Motorola P040 P080 VHF – schematics.pdf
| |– [1.5M]  Motorola P200 – operating instructions.pdf
| |– [1.5M]  Motorola PRO3100 UHF – schematics.pdf
| |– [2.3M]  Motorola PRO3100 VHF – schematics.pdf
| |– [2.3M]  Motorola PRO5150 – schematics.pdf
| |– [196K]  Motorola Systems Saber – UHF specifications, service manual.pdf
| |– [196K]  Motorola Systems Saber – VHF specifications, service manual.pdf
| |– [387K]  Motorola T4502 – instruction manual.pdf
| |– [3.5M]  Motorola T4512 – instruction manual.pdf
| |– [4.2M]  Motorola T5022 – User.pdf
| |– [3.2M]  motorola T6200 T6210 and T6220 instruction.pdf
| |– [5.2M]  Motorola XTL1500 users guide.pdf
| |– [2.2M]  Motorola XTL2500 users guide.pdf
| |– [9.7M]  Motorola XTS4000 basic service manual.pdf
| |– [6.0M]  Motorola XTS4000 detailed_service_manual.pdf
| |– [3.0M]  Motorola XTS4000 user service manual.pdf
| |– [3.6M]  Motorola XTS4250 – advanced model user guide.pdf
| |– [2.7M]  Motorola XTS4250 user guide.pdf
| |– [2.0M]  Motorola XTS5000 parts list.pdf
| |– [ 34K]  Motorola XTS5000 service aid sheet.pdf
| |– [5.2M]  Motorola XTS5000 user guide.pdf
| |– [5.7M]  MOTOTRBO DR3000 Repeater basic service manual.pdf
| |– [516K]  M-Series Owner_s manual.pdf
| |– [1.6M]  MSF 5000 maintenance and alignment manual.pdf
| |– [ 44M]  MSR2000 Control _ audio operation _ service manual.pdf
| |– [ 37M]  MSR2000 operation and service manual.pdf
| |– [8.3M]  MT1500 basic service manual.pdf
| |– [1.9M]  MTH500 Basic Service Manual.pdf
| |– [4.0M]  MTH500 Tetra Detailed Service Manual.pdf
| |– [1.2M]  MTH650 Tetra Basic User Guide.pdf
| |– [3.3M]  MTH800 TETRA basic service manual.pdf
| |– [4.3M]  MTH800 TETRA basic user guid.pdf
| |– [5.8M]  MTP700 Detailed Service Manual.pdf
| |– [2.1M]  MTP810 Ex TETRA basic service manual.pdf
| |– [2.1M]  MTP850 EX Basic Service Manual.pdf
| |– [8.4M]  MTP850 TETRA basic service manual.pdf
| |– [2.2M]  MTX Series detailed service Manual.pdf
| |– [3.8M]  MX300-S series service manual.pdf
| |– [4.0K]  p040-080_all_man
| | |– [1.9M]  10B67_UG.pdf
| | |– [2.3M]  10B68_UG.pdf
| | |– [163K]  13B29_CPS.pdf
| | |– [926K]  14B36_SG.pdf
| | |– [4.5M]  15B49_BSM.pdf
| | `– [ 40K]  ENLN4122A.pdf
| |– [2.7M]  PM400 Basic Service Manual.pdf
| |– [ 11M]  PM400 Detailed Service Manual.pdf
| |– [3.7M]  PR400 Basic Service Manual.pdf
| |– [9.5M]  PR400 Detailed Service Manual.pdf
| |– [1.8M]  PRO Series detailed service Manual.pdf
| |– [2.3M]  R-1011B Instruction manual.pdf
| |– [392K]  R-1013A operation _ service manual.pdf
| |– [6.9M]  R-1100A Operation manual.pdf
| |– [1.4M]  R-1150 R-1151 operation manual.pdf
| |– [2.5M]  R-2008C Operations manual.pdf
| |– [ 48M]  R-2200A service manual.pdf
| |– [3.5M]  R-2200 R-2400 operation manual.pdf
| |– [3.6M]  R-2600 SERIES Operator manual.pdf
| |– [1.0M]  Radius CM200 installation guide.pdf
| |– [769K]  Radius M100 M200 Owner_s manual.pdf
| |– [3.5M]  RLN-4008B service manual.pdf
| |– [2.7M]  S1051C S1053C operation _ service manual.pdf
| |– [4.4M]  S1067A operation and service Manual.pdf
| |– [ 12M]  S1318A S1319A S1320A S1321A S1329A operation _ service manual.pdf
| |– [267K]  SABER Portable Radios user_s guide.pdf
| |– [191K]  SABER Theory _ Maintenance manual.pdf
| |– [1.3M]  SM_GP68.pdf
| |– [3.9M]  Spectra Conventional Radio System Operating Instructions.pdf
| |– [458K]  Spectra Privacy Plus Operating Instructions.pdf
| |– [573K]  Spirit GT Operator_s manual.pdf
| |– [3.6M]  SSE 5000 service manual.pdf
| |– [8.4M]  Syntor X Maintenance and troubleshooting manual.pdf
| |– [3.3M]  TETRA MTH800 basic service manual.pdf
| |– [1.7M]  TETRA MTP850 basic service manual.pdf
| |– [ 10M]  XPR7000 basic service manual.pdf
| |– [ 11M]  XPR 7000 Seris basic service manual.pdf
| |– [4.0K]  XTL5000
| | |– [2.0M]  96C67-C_AX_UG_XTL5000_W3.pdf
| | |– [1.9M]  96C68-D_AX_UG_XTL5000_W4579.pdf
| | |– [3.2M]  98C38-O_v4.pdf
| | `– [622K]  9964416H03_O_XTL5000_AT_IM_Dual-Radio_CH.pdf
| |– [6.2M]  XTS1500 XTS2500 basic service manual.pdf
| |– [698K]  XTS3000 parts list.pdf
| |– [698K]  XTS3000 XTS3500 parts list.pdf
| `– [625K]  ZR310 service manual.pdf

A wireless door bell, activated by a wired door bell!

Winter time, is workshop time, spending several hours in the workshop every week, either in the ground floor workshop, or basement rooms – and on several instances, missed the postman! Especially on Saturday, when nobody else is at home, an I am waiting for some spare parts!

The simple reason, the door bell only rings in the office/apartment on the 3rd floor, but I can’t hear it in any of the workshops. This needs to be solved – but how? Running a wire through several floors is no option.

Browsing through online offers, I found some low-cost wireless doorbells (120 meters range!! probably, Chinese meters but fair enough) and came up with this scheme – the 3rd floor apartment door bell, which is integrated into a Siedle-brand HT411 door phone will trigger the transmitter of the wireless door bell, which in turn will give its sound in the workshop are.

This is the xbay offer – one transmitter, and two receivers.

That’s the HT411 with the transmitter mounted.

The door bell uses a transformer-less powder supply… let’s hope it will last.

Finally, the simple schematic using the “ring” signal of the HT411, which is 12 VAC to activate the door bell transmitter (with the button shorted, it will activate the received whenever power is applied!).

All is working loud and clear now, you push the main door button, then the HT411 will ring in the apartment 3rd floor, this in turn will active the wireless transmitter, and both receivers will sound in the 1st and basement workshop. Easy enough!

Holzmann BS 128HDR: “Holz” means wood, but this is a metal band saw!

For several years, I have been using hacksaws and similar tools, and other less suitable and dangerous tools to cut-off metal stock for milling and turning. Or, I used some friends’ equipment, which is troublesome and time-consuming – to travel to far-away places just to cut some metal.

With the space I have in the basement, there is no room to fit a large industrial band saw, and I wanted to get a machine that can also cut at an angle, for some welding and fabrication work. The machine selected, a Holzmann BS 128HDR is one of the common Chinese designs, but these are not all made equal, and the Holzmann looks like a good brand. Cutting capability is 125 mm diameter round, 100×150 mm square, which should be good for 99% of the work.

All came in two boxes, on a wooden pallet.

Some tests with 42CrMo4, and 26CrMo4 rod. It is cutting perfectly fine. Also checked with some square tubing, which can be challenging for some cheap band saws because of the thin-walled sections, but the 128HDR has a hydraulic break/mechanism, which provides smooth cutting action even for these more difficult materials.

For lubrication, you can use any type of ordinary oil, HLP 68 hydraulic oil works well and is cheap, with no smell.

Micrometer and Force: a time-stamped interface

For a special application that I can’t name here, we need to measure both deflection (length) with about 0.01 mm resolution, and force in the range of 200 N (=20 kg). The force measurement is needed with a few 10s of Hz of temporal resolution, for deflection ~10 Hz will be sufficient.

All this needs to be accomplished at a budget, so I decided to use a China load cell (20 kg range), with an HX711 converter board, and a digital micrometer dial (13 mm range, 0.01 mm resolution).

First, to the HX711. As per the datasheet, it can be run from an external clock source, not sure if this is necessary, but thought I give it a try. Spec range for the clock is up to 20 MHz (normally running at about 11 MHz), but the HX711 works well to 70 MHz and above. You don’t need to couple a lot of power, even at -10 dBm, it is still working. Anyway, by setting the clock control pin to HI, the HX711 will provide a data rate of 80 Hz. As with all analog-digital converters, there will be a trade-off for frequency vs. noise-free resolution, but for the application discussed here, even 10 bit would be enough, to serve the purpose.

For the digital dial – unfortunately, the industry (the Chinese digital caliper and dial industry) has not yet come to a decision to use a commonly available connector to get the signal for a digital caliper or dial into a cable. At least, they offer various types of data protocols, and with not too much sense detective work, you can figure out how to interpret the data. I user a Micro-USB connector, carefully soldered to the data output pads of the micrometer dial.

Some small wires were used to connect the USB connector to the board, to allow for some movement, and to ensure longevity even in an environment that has vibration, and people connecting the USB cable with not much care.
The dial is running on 1.5 V (a single button cell), so we need a small converter board, using half of a MC3302P quad comparator, to convert the 1.5 V logic to good old 5 V TTL logic. You can use any type of comparator of logic conversion circuit, even a single transistor may work. Anyway, I didn’t want to load the dial any more than necessary, and to improve noise immunity, added a 20 MHz low-pass (330 Ohm with 22 pF) to the input.

Here the rising edges, logic conversion board input (blue), vs. output (yellow). For the faster traces, the internal pull-up resistors of the ATMega8 were enabled. Not much effect anyway.

All the data are collected by a ATMEGA8-16PU, and sent to a host PC via a 115.2k RS232 link. This allows even wireless connections, with a serial-to-RS232 converter. Data are send in one direction only, from the ATMEGA8 to the PC. All measurements have a 16 bit time stamp, using the ATMEGA8 16 bit timer.

The 8 bit timer of the ATMEGA8 is used to capture the data from the micrometer, which uses a synchronous clock to transmit data – the risking edge of the clock will trigger an interrupt, INT0, and the timer will ensure that each data Frame is received properly (the timer will overflow after each received data package, to signal that the next clock edge will be the start of a new data package).

The dial transmission pattern: one data block is send every ~100 ms.

Some detail of the timing, for the current dial indicator interface, data are valid at the rising edge of the clock.

For the last bit, there is no falling edge of the clock.

For “0” logic state, the dial interface pulls down the data line for each clock pulse, and then releases it again for high. Not sure why that is, maybe it saves some battery power?

The data is transmitted as binary number, 24 bit, 0.01 mm or 0.005″ per count. The last 4 bits are uses for status and indicate a “-” display, and mm vs. inch.

That’s the full pattern of a transmission sequence from the HX711. Blue is data, yellow is clock.

Timing – data line changes states quickly after the rising edge of the clock signal.

This is the final data stream as received. Notice the time-stamped load cell and dial transmissions.

For those interested, here is the MCU code (AVG-GCC): loadc_d0.c

Workshop upgrade: Light fittings, and luminous efficacies

With the workshop basic repairs complete, how to set up a cost-effective lighting system?

Some items to consider
-I will be working there mostly after work, late in the evening, and mostly in the dark winter months. So I need daylight and bright light to keep focus.
-Diffuse light along will not be enough. I like the feeling of incandescent lights, so there need to be some work and bright direct lights.
-Some areas, like the stair, will need a separate light, which needs to be “ON” immediately after the switch is pushed. Same applies to the other lights – there should be no dimm start-up, flicker, or start-up delay.
-Light level needs to be high, because the main purpose of this room is the assemble, fix, and test high frequency/microwave assemblies, and fine-mechanical devices.
-Because this is a hobby, we need to keep expenses down, both for the initial cost (light fitting and lamps), and the running cost – electric power cost.

This is a plan of the room layout, rectangles mark the position of tables.

Essentially, two kinds of light sources have been considered – T8 fluorescent, for the background illumination, 8 pcs. 25200 lm total (EUR 5 per piece, including lamp and electronic started – a bargain). And 4 PAR38 30° LED down-spots (these replace the 108 W halogen lights, and have still have a nice glass body).

licht parathom

These are about EUR 13 per piece, and the light fittings are simple screw sockets E27 size, EUR 1.50 per piece.

licht raumplan

Some calculations done – total of 31 kilo-lm, 363 Watts (which is quite precisely found when checking the total current to the workshop with a wattmeter). ~85 Lumen per Watt, which is a very good value.

We will need to check the actual luminous intensity at the work surfaces later, because the lumens of the fluorescent tubes is not all going downwards (some reflected from the white ceiling and walls, some lost in the light fitting).

licht efficiacy

Life time these lights are rated for 25000 hours (LED), or 12000 hours (T8 tubes). This means, 3000~6000 hobby days (counted at 4 hours), so there should be no need to change these light bulbs and tubes any time soon.

New test lab and workshop: Renovation update

It has been a bit quiet here recently, not because of lack of activity, but more to the opposite. Currently, my workshop and test labs occupy on room in an appartment, 3rd floor (2. OG in German counting), and 3 basement rooms (mostly for soldering, assembly, and mechanical fabrication; plus 2 basement rooms in a house 2 hours drive from here… with some of the not-so-often-used heavy metal working machinery).

After some negotiation, I was able to get another room, which is on ground floor, well heated and rather constant temperature all over the year, and is has daylight – this all in a beautiful building that is even listed in the historic monument directory of the state. It has about 28 m2 floor space, and quite ideal for my needs to have a clean working area, for assembly of equipment, and detail testing. It is also much closer to the soldering workshop and parts storage in the basement, and will safe me from walking up and down 3 floor several times a day, during the final assembly phase or during repair works, which often require a combination of soldering, and difficult testing that could only be done so far on the 3rd floor. The basement is great, but it is too humid for operating vector network analyzer, and the like.

Now to the laborious part, the renovation. The had been used in the past as a meeting room for a motorcycle club (probably, in the 80s), and later as a workshop for remote-controlled model aircraft. During the last 3 years, it had been mainly used for storage, with the floor cover, walls etc, all aging away. Also, no internet connection of safe electric outlet available in the room. It took about 7 full days of hard work to get it up to requirement, including, removing all the junk, cleaning and fixing the walls, door, and wooden panels, removing several layers of old floor covers, and putting it all back together again. Another 3 days for all the cables, in particular, the network cables (all done using CAT7 LSZH 4x2xAWG23 S-FTP; one short section is CAT6 CCA PVC shield) and ethernet (CAT6) wall outlets.

Here a network map, mostly for my own reference, with the two servers (HTTP, SAMBA), running at 192.168.130 (this is the active server, a Dell Optiplex FX160 – it uses an ATOM processor, running Ubuntu, and is a really power efficient way to run such a system, 2 TB RAID0), and 192.168.77.140 (arctur, a Dell Poweredge server, 2×3 TB RAID1, used for backup of the active server, and also as a backup webserver in case of hardware failure or the FX160). All the switches were selected for low power consumption, to keep this green and low running cost. There are two WLAN transmitters, so now there is good bandwidth all around the (large) house and even in the basement and garage.

The WAN connection is via a cable modem, which is located in the 3rd floor apartment (2. OG), and works at 100 Mbps down, 6 Mbps up (this is good for now, usually getting abot 80~90 Mbps down, and the full 6 Mbps up, probably upgrading to a 100/100 Mbps connection next year).

A quick test of the network speed – by measuring the transfer speed from and to a ramdisk on the acrux server. Getting 50~70 Mbytes per second, from all locations of the network. That’s certainly fast enough.

werkstatt network map

This is a view for the power distribution, and network distribution box.

Ultra-cheap LED Spot Lights: Failure mode analysis, and some reverse engineering, and some concerns

Something amazing about the advent of LED technology for general lighting is not only the brightness, efficiency, and so on, but also the amazingly low price. Here, 20 light fixtures, including 3 LED elements each, 34 EUR total. That’s a bargain a friend of mine could not resist. But think twice, after about 1 year of occasional usage of these lights – several failed. Brightness is gone, some lightly flashing lights remains.

led-20-pcs-33-eur

Still the price is amazing – considering the price of a singe 1 W LED element, with about 1 EUR retail. Plus the case, heat sink, aluminum circuit board, heat conduction paste, external case, 3 lenses!! No idea how this is made in China, for about 1.5 a piece delivered.

led-1w-led-price

The first suspect – the drivers: each lamp has their own little driver box. Type S3W-0103.

led-driver-case

led-spot-down-light

The parts, and a good quality aluminum board, named CQ-LV8072. This is a universal board, found in many kinds of Chinese LED light fixtures.

led-driver-cq-lv8072-board

Tested the LEDs – turns out, one of the LED elements is dead, and this ruins the whole thing, as all three LEDs are arranged in a series circuit. We can fix this easily by replacing the LED elements, all three, with some good quality elements. Albeit, at almost non-economic cost. Hint – the case and be unscrewed with the heatsink turning vs. the outer case. No need to apply brute force like I did, to open it up.

led-driver-s3w-0103-board

Some reverse engineering reveals a rather simple, but practical circuit. Using S8050 and MJE13003 TO-92 transistors, and a little transformer.

led-driver-s3w-0103-schematic

As you can see, no protection elements, what if the input capacitor shorts out, or if some overvoltage blows the transistor. Could it set your flat on fire? Well, my guess is, yes.