Category Archives: Various

Various

Ultrasonic Pest Chaser: final design

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Following up on an earlier post, , design is now complete and a test unit has been completed.

First, a nesting box was made using 9 mm birch plywood. This can be varnished, to any color you like, and is in itself very much weather resistant. All edges and gaps were sealed with hot glue. For added stability, the bottom plate is inserted into a grove of the side and front panels.

rat chaser box1

rat chaser box2

rat chaser box3

rat chaser nesting box drawing

The driver was upgraded a bit, from the earlier version, by using a IRFP460 MOSFET. This is a very sturdy part, and will most likely not fail even under some severe operation conditions. It it can also be mounted to the heatsink in an insulated fashion, without any special washers, etc. – this is the main reason for selecting it.

rat chaser piezo driver schematic

The speakers are 2x KEMO L010,

rat chaser l010 speaker1

rat chaser l010 speaker2

and 2x PTI-1010; one of the PTI-1010 has its horn cut-off; both were fit with two layers of wrap foil to protect the membrane (PTI-1010 has a paper membrane, whereas the L010 has a plastic membrane).

rat chaser pti-1010 speaker

rat chaser pti-1010 speaker cut off

rat chaser pti-1010 speaker response

One key component of the setup, an inductor, in parallel with the speakers. This converts the capacitive load of the piezos to a much more well-behaved load, resonance frequency of the setup is a few kHz. The coil needs to be capable to handle currents of 1 Amp easily, otherwise, it will heat up and may even fail. The one used here may be a bit oversized but it was on hand and still has acceptable size and dimensions.

rat chaser coil

Three of the 4 speakers are mounted in Schedule 40 1.5″ PVC pipe (this pipe is common in the US and dimensions match well the dimensions of the speakers; you can use other types of plastic pipe as well).

rat chaser speaker piupes

The holes in the wood panels are precision machined, for a snug fit with the pipes. Hot glue is used to seal it all together and to firmly lock everything in place.

rat chaser speakers mounted

rat chaser speakers mounted2

Typical waveform during a test run, driving at somewhat above 12 VDC to test system durability… gate drive (yellow) and source-drain voltage (blue).

rat chaser waveform

Final testing…

rat chaser final tests

rat chaser final rear view

rat chaser final front view

Operated from a 12 Volts DC supply, the final tests show that the output voltage is pretty much in line with the allowable voltages for a series connection of two L010 speakers, and flat over the frequency band of interest.

rat chaser rms results

Various

Vintage Transistors and IC Stock: listing

3 Comments

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

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.

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

1 Comment

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?

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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

Various

TMS 2532 EPROM adapter: one byte every 50 ms…..

2 Comments

EPROM progammers seem like a thing of the past, still, they are very popular for test equipment repair, arcade games, and all kinds of other occasions where small amounts of data need to be stored in a bulky, fancy package.
Such programmers, mostly copies of the “Willem” design, are widely available, Made in China, and generally, these work pretty well. Well, as luck would have it, most of the ancient pieces of equipment use 2532 EPROMs, and just this kind is not supported by the common programmers, which support the 2732….. same capacity, different pin layout.

2732 pinout

tms2532-45

tms2532jl-45

To adapt the 2532/2532A (these only differ by their programming voltage, 25 V vs. 21 V – make sure the set it correctly) to the common 2732 programmers, the only thing you need is a small adapter, with a most complicated schematic (the only pins that change are 18, 20 and 21). Most of these EPROMs require programming pulse widths of about 50 ms, but often program OK with just 10 ms, or less.

2532 eprom adapter for programming schematic

2532 programming adapter view 2

2532 programming adapter view 1

Various

BNC 50 Ohm Termination: a rather surprising construction

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Doing some precise level measurement on 50 Ohm system, I came across this termination, Model 24931 28P296-1.

termination 1

It’s resistance, not quite 50 Ohms, but 51.1 Ohm… not that the DC resistance is the most important characteristics of a 50 Ohm termination, but nevertheless, a reason to check it.

This termination is constructed using a BNC connector, so I expected some kind of thin film resistor inside, maybe damaged by overload or age, leading to the incorrect resistance.

Opening it up, this it what I found:

termination rn55d 51r1 resistor

termination

The resistive element, a Vishay Dale R55D metal film resistor:
vishay rn55 resistor

And, in fact, it is a 51.1 Ohm, +-100 ppm/K tempco resistor. 0.1 Watts so it is running close to its limit already at 20 dBm! Don’t have the right tools here to measure ‘low frequency’ (< 2 GHz) SWR... but will check back home at the main workshop one time in the future, just for curiosity.

Various

ADCMP580 Ultrafast Comparator: it’s really fast!!

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Some experiments with a tiny part that has remarkable qualities: the Analog Devices ADCMP580. It is a comparator, and a very fast one indeed, based on a SiGe semiconductor.

adcmp580 features

Its features are true extraordinary – everything specified in GHz and picoseconds.
Well, can this be made work without a lot of money invested in a special HF or microwave board? Yes, it can. You just have to keep the wires short:

adcmp580 board

This test board was constructed by first soldering thin wires to the chip, and then mounting it on a small piece of perf board, with some epoxy glue. The output is wires, within less than 2 mm, to a (50 Ohm) SMA connector.

adcmp580 schematic

Measuring the performance characteristics is not an easy task. I used a 54750a sampling scope, with a 54751a 20 GHz bandwidth plug-in.

The comparator is fed by a 8642b signal generator, which is also used to trigger the 54751a plug-in.

At the output, a 13.5 dB attenuator is used, at least for some of the tests, to get best output SWR (to avoid issues caused by reflected signals). However, as it turns out, the 54751a has quite reasonable input SWR, and the connecters are better than it first seemed. So the attenuator can be left out. Still good to have some attenuators at the 54751a input, remember, this can only handle +-2 V, and no ESD!

adcmp 500 mhz square

adcmp 2 ghz square

In these tests, “squaring up” a 500 MHz and 2 GHz (!) signal. Rise and fall time are about 50 ps, not bad at all for the simple construction.

adcmp fft

FFT shows bandwith to 10 GHz and up.

Output power is also quite useful, 400 mV Vpp.

Various

Rong Hua (Bianhuan) “50 Watt” Travel Adapter: not enough iron, for this “wattage”

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In interesting find, Made in China, a 50 Watt travel adapter.

autotrans sc-20c a

autotrans sc-21c

autotrans sc-21c receptacle

autotrans plug

This is used to convert 220 V (despite the US plug!) to 110 V – same device also seems to exist for conversion from 110 to 220 V.

The build quality is exactly what you expect for less than USD 7. A crude plastic case, two screws, no protection circuits or fuses, and a rather small transformer.

autotrans inside

Total weight of the transformer – about 140 g.

Looking at some transformer tables, this is about 6-10 VA (=”Watt”, if you wish) nominal size. For autotransformers like this, the nominal size needs to be converted to the actual power rating, by using the conversion ratio (voltage ratio). P_nominal=P_actual*(1-voltageratio). I.e., for a 220 to 110 Volts transformer, the ratio is 0.5, and a 10 VA nominal transformer can handle 20 VA if configured as an autotransformer.

Quite obviously, 20 VA is not 50 VA – please use these these transformers with great caution, and only for really small appliances. Never leave it plugged in unattended, it might catch fire any time if overloaded, or if it fails!