Category Archives: Electronics

Electronics

Various

Vintage Transistors and IC Stock: listing

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For all folks that are into repair of vintage gear, here is a list of transistors (ICs, quartz crystals) that I have in stock. There are many more in stock, but these below have been listed and are stored in a way that I can find them easily… Primarily, these are for my private shop&repairs, but if you are in desperate need for one of these goodies, just shoot me a line (I may ask for a fee to cover my expenses&time).
These are mainly old Ge and Si transitors, and some amplifier ICs; listings of more outdated ICs – will be added soon.

Location Part Count

K-B35 AC151 – 15 Pcs
K-B35 AC188K – 12 Pcs
K-B35 AC187 – 2 Pcs
K-B35 AC181 – 2 Pcs
K-B35 AC151 – 1 Pcs
K-B35 AC184 AC185 PAIR – 2 Pcs
K-B35 AC185 – 2 Pcs
K-B35 AC550 – 1 Pcs
K-B35 AC150 – 1 Pcs
K-B35 AC424 – 1 Pcs
K-B35 AC179 – 1 Pcs
K-B35 AC178 – 2 Pcs
K-B35 AC176K – 1 Pcs
K-B35 AC117 AC175 PAIR – 1 Pcs
K-B35 AC117
K-B35 AC175
K-B35 AC173 – 1 Pcs
K-B35 AC171 – 2 Pcs
K-B35 AC153 – 3 Pcs

K-B36 OC70 – 6 Pcs
K-B36 OC72 – 1 Pcs
K-B36 OC74 – 1 Pcs
K-B36 OC71 – 1 Pcs
K-B36 OC74N – 2 Pcs
K-B36 OC75P – 2 Pcs
K-B36 OC75 – 5 Pcs
K-B36 OC171 – 1 Pcs
K-B36 OC304 – 5 Pcs
K-B36 OC612 – 1 Pcs
K-B36 OC318 – 10 Pcs
K-B36 OC603 – 1 Pcs
K-B36 OC306/2 – 4 Pcs
K-B36 OC308 – 1 Pcs
K-B36 OC305/1 – 1 Pcs

K-B37 BF245C
K-B37 BF245A
K-B37 BF245B
K-B37 BF244 – 2 Pcs
K-B37 BF225 – 2 Pcs
K-B37 BF224 – 4 Pcs
K-B37 BF223 – 2 Pcs
K-B37 BF258 – 1 Pcs
K-B37 BF458 – 4 Pcs
K-B37 BF324 – 1 Pcs
K-B37 BF422 – 4 Pcs
K-B37 BF716 – 2 Pcs
K-B37 BF715 – 2 Pcs
K-B37 BF467 – 1 Pcs
K-B37 BF891A – 2 Pcs
K-B37 BR303 – 2 Pcs
K-B37 BRY45-400 – 5 Pcs

K-B38 BC107 – 30 Pcs
K-B38 BC108 – 20 Pcs
K-B38 BC109 – 20 Pcs
K-B38 BC110 – 2 Pcs
K-B38 BC114 – 2 Pcs
K-B38 BC130 – 1 Pcs
K-B38 BC129 – 5 Pcs
K-B38 BC115 – 10 Pcs
K-B38 BC132 – 1 Pcs
K-B38 BC140-10 – 1 Pcs

K-B39 2N3019 – 4 Pcs
K-B39 2N3415 – 2 Pcs
K-B39 2N3440 – 1 Pcs
K-B39 2N3705 – 1 Pcs
K-B39 2N3704 – 10 Pcs
K-B39 2N3703 – 6 Pcs
K-B39 2N3638 – 4 Pcs
K-B39 2N3566 – 10 Pcs

K-B43 BC153 – 1 Pcs
K-B43 BC149B – 3 Pcs
K-B43 BC149C – 3 Pcs
K-B43 BC148B – 20 Pcs
K-B43 BC147A – 15 Pcs
K-B43 BC158A – 1 Pcs
K-B43 BC158B – 1 Pcs
K-B43 BC157 – 2 Pcs

K-B42 BSX45 – 8 Pcs
K-B42 BSX46 – 8 Pcs
K-B42 BSX49 – 20 Pcs
K-B42 BSY88 – 3 Pcs
K-B42 BUY48 – 1 Pcs
K-B42 BSY58 – 1 Pcs
K-B42 BSX81A – 30 Pcs

K-B40 BSY79 – 2 Pcs
K-B40 BCY96 – 2 Pcs
K-B40 BCY59 – 10 Pcs
K-B40 BCY58 – 6 Pcs
K-B40 BCW85 – 15 Pcs

K-B41 BC172B – 10 Pcs
K-B41 BC172C – 10 Pcs
K-B41 BC173C – 20 Pcs
K-B41 BC174A – 10 Pcs
K-B41 BC177 – 30 Pcs
K-B41 BC179B – 1 Pcs
K-B41 BC171B – 30 Pcs
K-B41 BC170 – 10 Pcs
K-B41 BC167A – 30 Pcs
K-B41 BC168B – 2 Pcs
K-B41 BC168A – 2 Pcs
K-B41 BC168H – 1 Pcs
K-B41 BC168C – 2 Pcs

K-B21 AF180 – 1 Pcs
K-B21 AF178 – 2 Pcs
K-B21 AF139 – 4 Pcs
K-B21 AF126 – 1 Pcs
K-B21 AF118 – 1 Pcs
K-B21 AF130 – 1 Pcs
K-B21 AF200 – 5 Pcs
K-B21 AF201 – 7 Pcs
K-B21 AF202S – 1 Pcs
K-B21 AF202 – 2 Pcs
K-B21 AF275 – 1 Pcs

K-B17 40361RCA – 13 Pcs
K-B17 40595 RCA – 3 Pcs
K-B17 40664 RCA – 1 Pcs
K-B17 40655 RCA – 2 Pcs
K-B17 40362 RCA – 15 Pcs
K-B17 40406 TCA – 2 Pcs
K-B17 40408 RCA – 1 Pcs

K-B19 AC117 – 8 Pcs
K-B19 AC122 – 10 Pcs
K-B19 AC122/30 – 3 Pcs
K-B19 AC124 – 5 Pcs
K-B19 AC125 – 10 Pcs
K-B19 AC126 – 9 Pcs
K-B19 AC123 – 5 Pcs
K-B19 AC127 – 11 Pcs
K-B19 AC123 – 3 Pcs
K-B19 AC128 – 10 Pcs
K-B19 AC121 – 1 Pcs

K-B20 AF116 – 1 Pcs
K-B20 AF160 – 3 Pcs
K-B20 AF114 – 2 Pcs
K-B20 AF115 – 3 Pcs
K-B20 AF116 – 4 Pcs
K-B20 AF106 – 4 Pcs
K-B20 AF109 – 1 Pcs
K-B20 AF121 – 11 Pcs
K-B20 AF122 – 1 Pcs
K-B20 AF125 – 2 Pcs
K-B20 AF126 – 12 Pcs
K-B20 AF127 – 2 Pcs
K-B20 AF200 – 1 Pcs
K-B20 AF137 – 1 Pcs

K-B12 2N527 – 4 Pcs
K-B12 2N1613 – 3 Pcs
K-B12 2N1711 – 6 Pcs
K-B12 2N1893 – 20 Pcs
K-B12 2N2218A – 2 Pcs
K-B12 2N2219A – 1 Pcs
K-B12 2N2907 – 9 Pcs
K-B12 2N2904 – 11 Pcs
K-B12 2N2368 – 3 Pcs
K-B12 2N2646 – 2 Pcs
K-B12 2N2926 – 8 Pcs
K-B12 2N2905A – 2 Pcs

K-B15 BSW43 – 2 Pcs
K-B15 BSS89 – 2 Pcs
K-B15 BSS97 – 1 Pcs
K-B15 BSW26 – 1 Pcs
K-B15 BSW39/10 – 1 Pcs
K-B15 BSW68 – 3 Pcs
K-B15 BSW66 – 12 Pcs
K-B15 BSW65 – 1 Pcs
K-B15 BSW67 – 1 Pcs
K-B15 BSW58 – 1 Pcs

K-B14 ASY12 – 1 Pcs
K-B14 ASY24 – 4 Pcs
K-B14 ASY426 – 1 Pcs
K-B14 ASY30 – 3 Pcs
K-B14 ASY70 – 1 Pcs
K-B14 AC141B – 1 Pcs
K-B14 AC135 – 1 Pcs
K-B14 AC126 – 4 Pcs

K-B16 BC181 – 1 Pcs
K-B16 BC182 – 10 Pcs
K-B16 BC183 – 4 Pcs
K-B16 BC207 – 20 Pcs
K-B16 BC208 – 2 Pcs
K-B16 BD115 – 1 Pcs
K-B16 BC190A – 2 Pcs
K-B16 BC217A – 1 Pcs
K-B16 BC214A – 1 Pcs
K-B16 BC213A – 5 Pcs

K-B13 BYT11-800 – 1 Pcs
K-B13 9144 50 P01 – 1 Pcs

K-A26 BB609A – 6 Pcs
K-A26 BB141B – 19 Pcs
K-A26 BB409 – 9 Pcs
K-A26 BA244 – 50 Pcs
K-A26 BAX13 – 1 Pcs
K-A26 DB3T – 2 Pcs
K-A26 ZTE1V5 – 30 Pcs
K-A26 ZPD8.2 – 12 Pcs
K-A26 ZPD16 – 14 Pcs
K-A26 ZPD3.9 – 3 Pcs
K-A26 ZDP5.1 – 25 Pcs
K-A26 ZPD15 – 9 Pcs
K-A26 ZPD8.1 – 25 Pcs
K-A26 ZPD4.7 – 7 Pcs

K-A28 XTAL 8.00M HC-49 – 100 Pcs
K-A28 XTAL 4.00M – 20 Pcs
K-A28 XTAL 10.23M – 50 Pcs
K-A28 XTAL 10.245M HC-49 – 20 Pcs
K-A28 XTAL 16.00M – 3 Pcs

K-A27 XTAL 20945K – 8 Pcs
K-A27 XTAL 5120K – 9 Pcs
K-A27 XTAL 16384K – 3 Pcs
K-A27 XTAL 18432K – 12 Pcs
K-A27 XTAL 10240K – 7 Pcs
K-A27 XTAL 92.575M – 6 Pcs
K-A27 XTAL 108.790M – 14 Pcs
K-A27 XTAL 108.765M – 4 Pcs
K-A27 XTAL 108.815M – 20 Pcs
K-A27 XTAL 108.74M – 7 Pcs
K-A27 XTAL 90.42M – 4 Pcs
K-A27 XTAL 21400K – 18 Pcs

K-A30 XTAL 77.42M – 4 Pcs
K-A30 XTAL 3.00M – 3 Pcs
K-A30 XTAL 20.00M – 2 Pcs
K-A30 XTAL 6.00M – 6 Pcs
K-A30 XTAL 61.375M – 7 Pcs
K-A30 XTAL 17.734475M – 6 Pcs
K-A30 XTAL 5.9904M – 2 Pcs
K-A30 XTAL 15600K – 5 Pcs
K-A30 XTAL 13.00M – 1 Pcs
K-A30 XTAL 21855K – 2 Pcs
K-A30 XTAL 18.00M – 4 Pcs
K-A30 XTAL 12.00M – 2 Pcs
K-A30 XTAL 6400K – 11 Pcs
K-A30 XTAL 33.8675M – 15 Pcs
K-A30 XTAL 4.00M – 5 Pcs
K-A30 XTAL 21.855M – 2 Pcs
K-A30 XTAL 16.00M – 1 Pcs
K-A30 XTAL 10.00M – 16 Pcs
K-A30 XTAL 8.00M – 8 Pcs
K-A30 XTAL 57.6575M – 11 Pcs
K-A30 XTAL 67.735M – 12 Pcs
K-A30 XTAL 24.00M – 6 Pcs
K-A30 XTAL 31.64M – 4 Pcs
K-A30 XTAL 5850K – 3 Pcs
K-A30 XTAL 20.945M – 2 Pcs
K-A30 XTAL 95.93M – 4 Pcs
K-A30 XTAL 31.64M – 4 Pcs
K-A30 XTAL 86.13M – 3 Pcs
K-A30 XTAL 10.230M – 2 Pcs
K-A30 XTAL 15.00M – 3 Pcs
K-A30 XTAL 9.8304M – 4 Pcs
K-A30 XTAL 7.3728M – 2 Pcs
K-A30 XTAL 20.5M – 2 Pcs
K-A30 XTAL 18.5925M – 5 Pcs
K-A30 XTAL 99.85M – 2 Pcs
K-A30 XTAL HC MOUNTING CLIPS

K-B50 MPSA43 – 3 Pcs
K-B50 MPSU45 – 5 Pcs
K-B50 MPSA56 – 6 Pcs
K-B50 MPSA63 – 15 Pcs
K-B50 MPSU95 – 5 Pcs
K-B50 MPS6514 – 6 Pcs
K-B50 MPS6513 – 2 Pcs
K-B50 MPSA06 – 2 Pcs
K-B50 MPS3702 – 2 Pcs
K-B50 16551 RCA – 6 Pcs

K-B51 2SC1681 – 7 Pcs
K-B51 2SC1815 – 1 Pcs
K-B51 2SC1921 – 3 Pcs
K-B51 2SC2002 – 3 Pcs
K-B51 2SC2368 – 2 Pcs
K-B51 2SC2062 – 1 Pcs
K-B51 2SC2274 – 1 Pcs
K-B51 2SC2471 – 1 Pcs
K-B51 2SC3071 – 2 Pcs
K-B51 2SC2611 – 2 Pcs
K-B51 2SC3150 – 1 Pcs
K-B51 2SC3114 – 3 Pcs

K-B53 2SC734 – 4 Pcs
K-B53 2SC828 – 2 Pcs
K-B53 2SC900 – 1 Pcs
K-B53 2SC929 – 1 Pcs
K-B53 2SC1507 – 2 Pcs
K-B53 2SC1213 – 2 Pcs
K-B53 2SC1096 – 1 Pcs
K-B53 2SC945 – 8 Pcs

K-B52 2SC114 – 4 Pcs
K-B52 2SC146D – 1 Pcs
K-B52 2SC460 – 2 Pcs
K-B52 2SC536 – 15 Pcs

K-B54 2SD1228M – 1 Pcs
K-B54 2SD525 – 2 Pcs
K-B54 2SD1541 – 1 Pcs
K-B54 2SD1453 – 2 Pcs
K-B54 2SD1455 – 1 Pcs
K-B54 2SD1135 – 1 Pcs
K-B54 2SD1046 – 1 Pcs
K-B54 2SD894 – 2 Pcs
K-B54 2SD613 – 1 Pcs
K-B54 2SD612 – 1 Pcs

K-B62 SS 3277-6 – 2 Pcs
K-B62 S2003MSI – 1 Pcs
K-B62 E505 – 1 Pcs
K-B62 TDA1412 – 2 Pcs
K-B62 ZTX502 – 2 Pcs
K-B62 SIP5172 – 3 Pcs
K-B62 S7504 T1045C – 1 Pcs
K-B62 S-300-E – 7 Pcs
K-B62 CS9011E – 1 Pcs
K-B62 S2017 T1907A – 4 Pcs
K-B62 SFT47 – 5 Pcs
K-B62 TP5368 – 4 Pcs
K-B62 S6157 – 2 Pcs

K-B55 2SD313 – 1 Pcs
K-B55 D45H7 – 2 Pcs
K-B55 2SD77 – 1 Pcs
K-B55 2SD471 – 1 Pcs
K-B55 2SD476 – 2 Pcs

K-B56 2SB22 – 1 Pcs
K-B56 2SB54 – 3 Pcs
K-B56 2SB56 – 2 Pcs
K-B56 2SB77 – 12 Pcs
K-B56 2SB405 – 2 Pcs
K-B56 2SB329 – 9 Pcs

K-B57 2SB536 – 1 Pcs
K-B57 2SB544 – 1 Pcs
K-B57 2SB595 – 1 Pcs
K-B57 2SB910M – 1 Pcs
K-B57 2SB669 – 1 Pcs
K-B57 2SB649 – 1 Pcs

K-B60 ZTX238 – 20 Pcs
K-B60 ST1-B N52 – 1 Pcs
K-B60 ZTX3904 – 6 Pcs
K-B60 ZTX415B – 7 Pcs
K-B60 ZTX3707 – 6 Pcs
K-B60 ZTX3706 – 1 Pcs
K-B60 ZTX3903 – 6 Pcs
K-B60 ZTX327 – 1 Pcs
K-B60 ZTX3708 – 2 Pcs

K-B61 TDA1670A – 1 Pcs
K-B61 L298 – 1 Pcs
K-B61 TLP298KV – 1 Pcs
K-B61 AN5521 – 1 Pcs
K-B61 SANYO-002 HDK-U – 1 Pcs
K-B61 µPC1378H – 1 Pcs
K-B61 LA7837 – 1 Pcs
K-B61 LA4430 – 1 Pcs
K-B61 TDA4600-2 – 1 Pcs
K-B61 LM2877P – 1 Pcs
K-B61 KIA7217AP – 1 Pcs
K-B61 LAS6350P – 1 Pcs
K-B61 AN5265 – 1 Pcs
K-B61 LA4440 – 1 Pcs
K-B61 TA7250BP – 1 Pcs
K-B61 LL6207 – 4 Pcs
K-B61 HYBRID SMS 3112 207 10503 – 1 Pcs

Magnetic

ST LIS3MDL Triaxial Magnetic Sensor: a lot of data, for such a small VFLGA package

2 Comments

For some project to be discussed later, a magnetic sensor will be an essential ingredient. Time for some preliminary tests, using ST Microelectronics LIS3MDL sensor.

lis3mdl package

Just 2x2x1 mm, and 12 contacts! Not an easy tasks, but as you can see, wires can be soldered to all these contacts. Will be covering this with a bit of expoxy glue soon.

lis3mdl closeup

The “schematic”, it is rather simple. All is connected to a small ATmega32L board, running at 16 MHz, and handling the USB interface used to get the data out.

lis3mdl schematic

The board, mounted to a box, showing the XYZ coordinates.

lis3mdl box

After some configuration and programming, believe it or not, there is actually a signal on the DRDY (data ready) line – this is set high, whenever data is available. The AVR uses the configuration register to query data acquisition status. But DRDY could be used as well. For best noise performance, the LIS3MDL is run at its fastest and most precise setting, getting 1 sample every 6.5 ms – about 155 Hz data rate. Date is then decimated to 1 point per second, transferred to a PC via USB, and further decimated to 1 point per minute.

lis3mdl drdy signal 155 hz 2 ms xdiv

Some calculations later – the total field (data points: one per minute, ticks show 6 hour intervals):

lis3mdl total field 1 point per minute

Inclination – New York (actual, correct data: -13 deg Declination, 67 deg Inclination, total field: 52 Microtesla, about 0.52 Gauss).

lis3mdl inclination

Declination (absolute value – acutual declination would be negative).

lis3mdl declination

… well, not quite accurate yet, but close enough! Some variations seem to be due to temperature, others, not so sure, living next to a train line here, and a lot of magnets around, including, strong magnets. And the cardboard box, it is not really square and rectangular, nor is the alignment perfect.

For those interested, the AVR code snippet used to get the data from the mm-size “brick”: lis3mdl_avr

Various

Micro Networks Corporation MN3010 DAC: long term stability test of a rather unconventional DAC

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Recently, I found a MN3010 chip, in a pretty fancy and unconventional ceramic/gold/metal package. Turns out, it is a DAC; but not a normal DAC – rather a 2 digit BCD DAC.

mn3010 top

mn3010 gold side

mn3010 spec

MN3010 Datasheet

mn3010 test board

Quickly hooked it up to an 8 bit port, counting in cycles, from 0 to 255… This is the resulting output:

mn3010 bcd counting up scope

Bottom line is about -13 volt, top is 0 V. 2 V per vertical division.its

Notice the strange steps – this is a clear indication of the “BCD” nature of this chip – 4 upper bits encoding the output in 1 volt steps, and the lower 4 bits encoding the 0.1 V digit.

Now, to put it to a test – re-programmed the counter to actually count in BCD digits, from 0 V, to -10.9 V – which is a bit above the specification – the device is supposed to output 0 to -10 V.

mn3010 input vs output

Next, let this thing run for about 18 hours recording the voltage at each of the allowed input codes, using a HP 34401A 6.5 digit volt meter, using a little program and GPIB cable.

These are the output voltages, as a function of time, for certain fixed codes:

mn3010 18 hour drift

… I would say, the DAC is rather stable: it consumes about 0.5 Watts, and is running warm, but it appears to be reasonably insensitive to temperature, far better than 0.1 LSB (more like 0.01 LSB!)

After recording all the numbers, some number crunching using well-known Excel…. multi parameter linear regression.

mn3010 regression analysis

Regression analysis yields the voltage values associated with the bits, they are close, but the 0.2 and 0.4 V have some deviation. It’s a pitty I didn’t test this device about 30 years ago, then we would know if this deviation is due to age, or just the result of normal manufacturing tolerances (certainly all within specified limits).

mn3010 bit values from regression

mn3010 bit value dev

Here, as a last graph- the total deviation (which contains all error sources, including any offset errors), accordingly, the output tends to be 0.005 to 0.02 V (0.05 to 0.2 LSB) low, digital code vs. actual output voltage. Pretty good (limit is +-0.25 LSB), still.

mn3010 total dev

Now, let’s keep this device another 30 years, and repeat the test…… I will keep you posted.

Attenuator calibrator (objective: a really precise and accurate apparatus)

Micro-Tel Precision Attenuation Measurement Receiver: an all-electronic manual for an almost all solid state device

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Look at what I have here, finally, an (well, almost, 1 page missing) PDF manual for a Micro-Tel 1295 Precision Attenuation Measurement Receiver. Including all schematics…

1295 manual

…a pleasure for the eye and joy forever!

1295 a4 if module

1295 a3b6

If you have any rare manuals, let me know, much appreciated!

Various

Ultrasonic Pest Chaser: scare way all the rats, squirrels and other furry creatures….

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Winter approaching, all the pests of the world would like to hibernate in my attic. And around the house, an increasing number of squirrels is feeding off the birds’ food. But hold, for every problem, there is an electronic apparatus that can solve it, it this case: an ultrasonic pest chaser.

First of all, we need a random ultrasound signal generator. Tests have shown that frequencies in the 18 to 30 kHz range are best, and that not all animals respond to the same frequencies. So we need a cover-all solution. Furthermore, animals will get used to certain noises, even 105 dB ultrasonic noise. So we need to build-in some surprises. Sometimes, the machine will be quiet, then it will come up with all kinds of nasty sounds. Sure enough, at high level.
This is achieved by a little microprocessor, an AVR ATmega8, but you can use any micro of your choice. Please check out the source code – the sounds are generated by using certain pre-set sequences of breaks, durations and sound frequencies, and these are rotated in a repeated (but very long) pattern. The pattern won’t repeat to soon, because prime numbers have been chosen for the lengths of the sequences, thus, they appear almost random for the listener (only those with ears able to receive high frequency noises like this).
There is also a LED indicator signaling the ON state of the ultrasound. Even if you can’t hear it, please stay away from the speakers – these >100 dB may damage your hearing without any prior notice. Keep children away. As always, this post is for your education only, don’t try it at your home!!

marder sig gen schematic

The signal generator schematic is as simple as it gets – frequency is derived from a 4 MHz crystal, via TIMER1 of an ATmega8. Some auxiliary circuitry is used to derive a 5 VDC rail from the supply voltage (anywhere from 10 to 30 V, depending on the speaker).

marder power driver schematic

The power driver uses two NPN transistor and a MOSFET to provide sufficient current for the speaker. The speaker, some are under test, more about them later. Piezo high frequency speakers are the speaker of choice for this application.

marder signal gen board

Some pictures of the boards – all build on plated-through FR4 perf board, this will last a long time even when use outside.

marder driver board

A test, using a 10 Ohm load resistor, and a 40 kHz drive signal. The MOSFET is switching nice and fast, no issues. For the speaker, it might help to couple the (capacitive) piezo with a suitable inductance, and to add a DC decoupling capacitor (about 1 µF, pulse resistant type). You can see that the resistance of the MOSFET in ON state is about 1 Ohm, current is about 1 Amp, for a 12 VDC supply voltage – and 0 V is one graticule up from the bottom of the scope.

marder 40 khz test 2 v ydiv

Finally, a test of the circuit, frequency (Hz) vs. time (seconds). This nicely shows the “random” nature of the noise, with breaks of various lengths in between noise bursts. Poor squirrel, poor rat – but they have a choice: keep out of harm’s way, and out of the attic!

marder signal test

This is the microprocessor code, avrgcc.

marder1_151130

Various

Compact Fluorescent Lamp (CFL) TP120-13MSL, 13 Watt: some circuit analysis

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Quite honestly, I don’t like these compact fluorescent lamps (CFLs) too much. They save energy, maybe, but the light produced is not really appealing, and in the long winters here, some extra heat produced by an ordinary light bulb is much appreciated anyway.

cfl lamp t120

Having a few defective CFLs around, I could not resist to open one up and check inside. That’s the schematic.

cfl compact fluorescent lamp schematic

More can be found at other sites, this is quite comprehensive: CFL Schematics (LabKit).

cfl circuit

The circuit uses a rather small ring core transformer, two primaries, for feedback, 3 turns each, and a secondary, 9 turns. Two transistors MJE 13003 (in TO-92 package) are arranged to form an oscillator circuit. These transistors can handle 600-700 V no problem. The DIAC (BA3) forms the starter circuit, giving a first few pulses to the oscillator, when the lamp is still high-impendance (prior to ignition). Once the lamp has started, the D5 diode will disengage the start-up circuit.

The transformer:

cfl transformer t1

Below, wrapped in blue tape, and with an E-E ferrite core, that’s the choke, about 1.6 mH inductance, which is part of the lamp’s resonant tank (along with C3, C5, and the secondary transformer – and C7, which will play a minor role, because of its comparatively large value).

cfl coil l1

Various

HP 8481A Power Sensor: why are they all blown?

13 Comments

A remarkable HP product, the HP8481A sensor. It appeared on the market about 1974, and still today, these devices are very much thought after. It works from about 10 MHz to 18 GHz, -30 to +20 dBm.

Quite some detail about this sensor can be found in the HP Journal, 1974-09 edition (pages 19ff).
There is says that the sensor can withstand 300 mW power, and even 0.5 Watts for seveal days. Still, there are many sensors around that are blown – why do so many people connect them to 0.5+ W transmitters and destroy them along the way? I have no idea!

Here, a quick glance at the internals:

8481a view

8481a thermocouple chip

8481a thermocouple cross section

8481a schematic hp

8481a schematic

8481a exploded view

8481a power sensor

8481a shield

8481a open

8481a internal

8481a ferrites

8481a connector

8481a sensing element

Note the capacity values – measures: 3.5 nF at the input, 3.0 nF at the output. This is all real gold on sapphire substrate!

8481a capacitor values

Noise Meters and Noise Figures

HP 8970A Noise Figure Meter: A7 voltmeter assy fix

2 Comments

Finally, some capacitors arrived, Panasonic ECW FD type, polypropylene dielectric. These are very much suitable for any type of active filter or sample/hold circuits, thanks to their good capacitance stability, and low dielectric absorption.

8970a a7 assy cap replacement ecw-fd2w154jq

8970a ecwfd capacitor data

Dielectric adsorption, not something specified on the datasheet. So I did a quick test, using a 50 Volt power supply, a 100 Ohms resistor, and a high-impendance (10 GOhm or more) voltmeter. Test follows this sequence:
(1) Charge capacitor for about 10 minutes; make sure to limit charge current to a few 10s of mA.
(2) Discharge for 10 seconds, using a 100 Ohm resistor.
(3) Measure voltage and record maximum value (V_measured) – typically, this takes several seconds.
(4) Calculate: V_measured/50 Volt *100%, the number obtained is a measure of dielectric absorption, in %.

Results: 0.005% for the ECW FD (Panasonic brand, PP dielectric), and 0.09% for the original cap, HEW-446 series (TRW brand, PET dielectric). Not bad, rule of thumb says that PP has 5x lower absorption than PET, well, but don’t quote me on the numbers measured – these are just rough estimates, fair enough. Needless to say, the new capacitors will outperform the original ones by far – and hopefully last as long, or longer, 30+ years….

Another detail. Note the line on the top side of the A7 board, close to one terminal of the capacitor? This is the outer winding of the capacitive layer. This goes to ground. The ECW FD aren’t marked for their winding direction (these are non-polar caps, but still, there is an outer layer of foil, and an inner layer, and the outer layer does pick up more noise, and thus needs to go to the lower impedance connection). But the winding direction can easily be determined, just connect the capacitor to an oscilloscope probe, and hold the part between your fingers – then, swap the probe (switch ground and hot connection). You will see different levels of noise on the screen, mainly, 50/60 Hz hum. Select the connections for lowest noise, and the ground lead of the oscilloscope probe will then indicate the outer layer of the winding. Best, mark it with a felt pen.

8970a a7 assy caps replaced

R820T/RTL2832U USB SDR: Various hacks and measurements

USB RTL SDR 28.8 MHz Reference: dividers, PLL, success

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With the 28.8 MHz VCO design established, all we need to move this project on are divers for the 28.8 MHz (VCO) and 10 MHz (Reference) signals, a slow-acting PLL, and some auxilliary circuitry to feed the 28.8 MHz back to the RTL SDR.

The 28.8 MHz and 10 MHz signals are AC coupled with about 1 kHz input impedance, this is quite common for any 10 MHz reference signal input (used for various kinds of test equipment). These signals are then amplified/limited by unbuffered inverters, 74HCU04. This is a very cost-effective and easy solution, the HCU04 has push-pull outputs, and input clamping diodes. Still, some clamp diodes have been added for the 10 MHz input, just in case.

28.8 mhz divider chain schematic

Looking at 28800 kHz, and 10000 kHz, 400 kHz is the largest common denominator. Accordingly, we need :72, and :25 division factors.

Division of the 10 MHz down to 400 kHz is accomplished by two 74LS90, but you can use other TTL decade dividers, these were just the circuits I had in stock.
28.8 to 400, a bit more tricky, first, divided by 8, using a 74LS293, and another LS293 that has two diodes, acting as an “OR”, to reset the counter when count 9 is reached.

Both 400 kHz signals are then compared use a flip-flop phase comparator, conveniently packaged in a 4046 PLL. For convenience, and to avoid digital noise on the 12 V rail powering the VCO, the 4046 is powered only from 5 V. This somehow limits the tuning output range, from close to 0 V, to about 3.1 V.

The loop filter is very slow acting, tens of seconds, because the objective of this PLL is to correct long-term drift of the 28.8 MHz reference, introduced by temperature, Xtal drift, etc., but otherwise not to impact its noise and oscillation characteristics.

28.8 mhz pll and loop filter schematic

The VCO (see earlier post, VCO design) uses a fixed capacitor to set the tuning offset, this was changed to 4.4 pF, and finally to 2.2 pF, to properly center the tuning voltage (V_tune, output of the PLL loop filter buffer) within the 4046 output range, at roughly 1.7 V.
Extentensive testing was carried out the ensure that the VCO starts up properly, even if extreme V_tune voltages are applied; as the 28.8 MHz Xtals used in the USB RTL SDR devices may vary, you will need to check the required tuning range and pullability of the Xtal. Some Xtals oscillators will stop oscillating, if you pull to frequency up or down too much, which might happen during PLL start-up. This can lead to an undesirable lock-up condition.

Here are the tuning characteristics, for 2p2, and 4p4 pF VCO capacitor values.

28.8 mhz tuning

This is the divider and PLL board. Sure it would be much nicer to have everything completely separated, in shielded cans, etc., but I did not go to such effort. Later testing will reveal if it has any bad consequences for the 28.8 MHz phase noise, but so far, I don’t see much noise – will do a more in-depth comparison later.

28.8 mhz pll boad

Noise Meters and Noise Figures

HP 8970A Noise Figure Meter: defective A7 voltmeter assembly – temporary fix

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A broken noise figure meter, not really a good situation with so many tasks related to noise figures at hand, not only the noise source projects. So, another look at the A7 assembly. With the suspect TL072 opamp replaced by a less suitable, but known-working subsititute, the fault still comes and goes – well, maybe, in the end, the TL072 is not even at fault? There aren’t so many components around, so I checked for all the likely and unlikely things, and found – a defective integrating capacitor!

See the schematic – there are two of the same kind – C4 is the bad one (integrator cap; upper orange frame), C3 (auto-zero; lower orange frame) is fine.
8970a a7 assy schematic c3 c4 capacitors

0.15 µF, 100 V, Mylar, 1982 vintage, and after all these years, somehow, it has developed an intermittent fault (the first Mylar cap with such fault I have ever seen).

trw hew-446 0.15uF 100vdc

With no spare at hand in my tiny New Jersey workshop, I decided to swap the caps, using C3 as C4, and temporary mounted a 0.1 µF film capacitor (Wima FKM) as C3. For the auto-zero function, the exact value and leakage of the capacitor won’t matter so much, anyway.

a7 assy swapped cap

See, how nicely it works: red – integrator charged from input voltage; blue – integrator discharged by reference voltage; grey – auto-zero; this sequence repeats over and and over again, and the duration of the reference segment is determined, after applying the input voltage for a fixed time (all controlled by LS TTL logic on another board).

0.25 V input, 1.2 V reference.
a7 voltmeter 0.25 v input

1.0 V input, 1.2 V reference.
a7 voltmeter 1 v input

Some quick thoughts about the capacitor; typically, Mylar/PET/polyester caps aren’t the best for integrators, because of higher leakage current, and dielectric absorption, compared to, say, polypropylene caps. Maybe, at the time, HP engineers determined that the TL072 leakage current, and other leakage currents on the board would be much larger than any capacitor leakage current; or, they didn’t want to introduce specialized parts – these axial Mylar capacitors of TRW brand were quite common in 1970- early 1990 era HP gear. These are actually not metallized Mylar/PET, but film-foil capacitors (using discrete plastic and metal foil, similar to Wima FKS-3).

Look inside the dead cap – there actually are the plastic and metal foils.
mylar and metal film

For the next few weeks, this configuration will be sufficient; then I will check capacitor stock back at the main workshop; most likely there are some Wima/Epcos/TDK FPK or MKP (PP dielectric foil-foil or metallized PP foil) capacitors around; if not, then I will just fit a pair of good Mylar caps.