Category Archives: Various

A13 30 MHz Reference Oscillator: a reasonably quiet oscillator, and a noise cable

2016/02/08 Simon Leave a comment

A nice little oscillator assembly came my way, supposed to generate about 17 dBm at 30 MHz. Nothing special at first glance, but after checking out its internals, it appeared to be worth a more careful look.

A hand-made box, and even more labor intensive assembly work inside. All build by point-to-point wiring, using only the best components available, glass trimmer caps, filters, mica caps – most of these parts are still available today – about 100 USD bom, at least.

After a bit of reverse engineering, here the schematic, a modified Colpitts oscillator. Note: base resistor of 2N5109 is 150 Ohms.

To measure phase noise, connected it to my HP 3585A spectrum analyzer (this is really a great piece of equipment, a bit heavy, but still best of class noise performance and holding this title for the last 35 years….). Connected the oscillator via a 6 dB attenuator, to provide a clean load to the output, rather than dealing with the imperfections of cables, adapters, and the analyzer input.

Quite shocking, all this noise. The green trace shows the analyzer noise floor. Check, and re-check, still a lot of noise. Too much to be true. After 3 hours of tests, found the issue: a defective BNC cable. Center connector was fine, but both shields were non-connected.

A bit more examination of these cable shows their lousy construction. Not bad for 2 dollars a piece, but you get what you pay for…. the shield is not even reaching to the plug – there is a 5 mm gap from the screen end, to the actual plug. So even if all would have been connected fine, the would still be a lot of leaking, from inside out, and outside in.

Notice the BNC plugs – these have a somewhat uncommon construction, the dielectric is covered at the front… not quite according to BNC standard.

Clearly visible, the cold solder joint…. Turns out, both ends were open-circuit at the shield.

Finally, using a good quality BNC cable (also, using LMR-195 double-screened cable). Looking much better. Noise is down -115 dBc at 10 kHz from carrier. It’s good, but not great. I think one could do better, especially, considering all the pricy parts, and high-quality construction. A good target for a Colpitts osciallator would be better than -130 dBc, at 10 kHz separation.

Note the pink trace – this is the bad cable, terminated with a 50 Ohm resistor (with the shield broken at both sides, it is actually a 1 meter wire antenna, with an open-circuit 50 ohm resistor at the end).

Various

440 MHz ISM Band Amplifier: a few extra milliwatts….

2016/01/10 Simon Leave a comment

There are quite a few devices that use the ISM (industrial-scientific-medical) band at around 440 MHz to transmit information, like, remote thermometers, or to control some installations, like, garage doors, or for personal communications, like, LPD radios, or cordless headphones. Another general term for these devices is SRD – short range devices, and the short range is ensured by a typical maximum power of 10 mW, chiefly, 10 dBm.

In some cases, it may be desirable to boost the output a bit, especially, if you are out in the woods, or for some experimentation of various kind. Be aware, depending on your country of residence, there may be limits to the allowable power of SRD units, make sure you know the rules!

Various MMIC gain blocks exist to provide amplification and output power, but why not go for a discrete transistor solution, using a BFG541 (or BFG591) device. These 9 GHz/7 GHz transistors are SOT223 devices, very robust and easy to work with, and they are pretty low cost, less than 0.5 USD a piece. All the other parts needed are just sub-1-cent capacitors and inductors, except, maybe, for the electrolytic cap.
The small inductors and capacitors at the input/output improve the input/output match (to 50 Ohm impedance), and provide some low-pass filtering (about 800 MHz).

The test circuit on a piece of perf board (adhesive copper tape used for the back plane). Note that this test circuit still has variable capacitors that were replaced by fixed caps in the final design. Also the bias voltage trimmer can be replaced by fixed resistors, it was just added here for convenience of bias current adjustement during test.

The gain measurements were done at +7 dBm input power. To get accurate results and to avoid overload of the VNA input, a 6 dB attenuator was attached to the output (with 2 Watts load capability), followed by a test cable, and with a 20 dB attenuator, directly at the VNA input. This gave about 26 dB (plus minor cable losses) of attenuation, or about -5 to 0 dBm at the VNA input, which is good. The gain offset introduced by the attenuators was removed by recording a reference trace and subtraction from the measured gain trace.

As you can see, well above 15 dB gain, and all reasonably flat (note that this is not the true gain, but the limiting characteristics; gain, at lower input power, is larger). We don’t want too much gain above 800 MHz, otherwise, amplification of harmonics and spurious signals comming from the SRD output (which typically is not filtered very well) could interfere with other communications.

Here a few plots of the output power, at various input levels.

To get about 200 mW output power, about 5 mW (7 dBm) are enough, at 440 MHz, even less, at lower frequencies (in case you need to amplify other signals). 200 mW should be plenty for all practical applications related to SRD or ISM personal devices.

Various

Vintage IC Stock: listing

2015/12/31 Simon Leave a comment

For all folks that are into repair of vintage gear, here is another list (earlier list: Vintage Transistors) of circuits 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).
Note that I don’t keep exact stock lists – some of the parts may become unavailable over time. Listings of more outdated ICs – will be added soon.

Location Part Count

K-T01 LA7212 – 1 Pcs
K-T01 M58653P – 1 Pcs
K-T01 LM3915N – 2 Pcs
K-T01 TD62103P – 1 Pcs
K-T01 NE5534AN – 1 Pcs
K-T01 LC24085P – 1 Pcs
K-T01 LC74084P – 1 Pcs
K-T01 UAA170 – 1 Pcs
K-T01 TBA120 – 1 Pcs
K-T01 TBA120S – 1 Pcs
K-T01 SAB2022P – 1 Pcs
K-T01 SAB1046P – 1 Pcs
K-T01 SAJ110 – 1 Pcs
K-T01 TDA2721 – 1 Pcs
K-T01 WD1100V-12 – 1 Pcs
K-T01 TDA2710/1 – 1 Pcs
K-T01 TDA2730 – 1 Pcs
K-T01 TDA3780 – 1 Pcs
K-T01 TDA2560/3 – 1 Pcs
K-T01 TDA1054M – 1 Pcs
K-T01 SAB1009B – 1 Pcs
K-T01 TAA611 – 3 Pcs
K-T01 CA3081 – 4 Pcs

K-T02 Z85C3008PSC – 1 Pcs
K-T02 SN76477N – 1 Pcs
K-T02 4N33 – 3 Pcs
K-T02 TDA2151 – 1 Pcs
K-T02 TDA2160 – 1 Pcs
K-T02 KM6264AL-10 – 1 Pcs
K-T02 MM74C906N – 1 Pcs
K-T02 SN7493AN – 1 Pcs
K-T02 ICM7049AIPA – 2 Pcs
K-T02 SN16913G – 1 Pcs
K-T02 MAX690A – 1 Pcs
K-T02 TL7705ACP – 1 Pcs
K-T02 TDA2320A – 1 Pcs
K-T02 SAJ110 – 1 Pcs
K-T02 TDA1950 – 1 Pcs
K-T02 HM4334P-4 – 1 Pcs
K-T02 TDB0556A – 3 Pcs
K-T02 SN76660N – 3 Pcs
K-T02 TC5508P-1 – 12 Pcs
K-T02 UA733CN – 2 Pcs
K-T02 TAA710 – 3 Pcs
K-T02 TDA3562A – 1 Pcs
K-T02 CA3083 – 1 Pcs
K-T02 ULN2111A – 1 Pcs
K-T02 SAA1027 – 1 Pcs
K-T02 TDA2790 – 1 Pcs
K-T02 TDA2740 – 1 Pcs
K-T02 TDA1170S – 1 Pcs
K-T02 TDA3770 – 1 Pcs
K-T02 TDA4942 – 1 Pcs
K-T02 TBA440C – 1 Pcs
K-T02 TDA1940 – 2 Pcs
K-T02 TDA2591 – 1 Pcs
K-T02 TDA2730 – 1 Pcs
K-T02 TAA630S – 1 Pcs
K-T02 TDA1180P – 1 Pcs
K-T02 TA7630P – 1 Pcs
K-T02 MC14584BCP – 1 Pcs
K-T02 709CJ – 1 Pcs
K-T02 MC1307P – 1 Pcs
K-T02 WIC7015 – 1 Pcs
K-T02 V4001D – 1 Pcs
K-T02 MC14503B – 1 Pcs
K-T02 TDA2140 – 1 Pcs
K-T02 M3-7603-5 – 1 Pcs
K-T02 N82S25 – 1 Pcs
K-T02 N8T10B – 1 Pcs
K-T02 L6506 – 1 Pcs
K-T02 TCA830S – 2 Pcs
K-T02 TAA930 – 1 Pcs
K-T02 TDA2522 – 1 Pcs
K-T02 TDA2532 – 1 Pcs
K-T02 SN76001ANQ – 1 Pcs
K-T02 TDA7250 – 2 Pcs
K-T02 WD1100V-03 – 1 Pcs
K-T02 R5620 – 1 Pcs
K-T02 WIC6020 – 2 Pcs
K-T02 LM339N – 1 Pcs
K-T02 DS8836N – 2 Pcs
K-T02 A10N – 1 Pcs
K-T02 TA7171P – 1 Pcs
K-T02 9602PC – 1 Pcs

Various

IBM Thinkcentre M50 P4 3 GHz: electrolytic capacitor repair

2015/12/30 Simon Leave a comment

One of my computers, a trusty IBM Thinkcentre Desktop, decided to fail on me. Symptoms – sometime it starts up normal, sometimes it doesn’t. Already hangs at the boot screen. Smells like a hardware issue, and in fact, it is a hardware issue – with some electrolytic caps (note the brown substance leaking out from the top vents; fortunately enough, no damage to the board).

Electrolytic cap failure are a very common feature of modern consumer electronics, the remarkable thing here: only some of the caps failed – 1500 µF, 10 V, and 1000 µF, 10 V. Maybe these see particular load, or they are from a batch that wasn’t all that good. All were high quality Nichicon brand, 105°C, HM series, specially designed for PC motherboards, low impendace, etc.

Board with new caps installed…

All caps were replaced by 1000 µF, 25 V – these were the only caps I had available with the given footprint and capacity range; 100 n X7R multi-layer caps were added (solder side), hopefully, to prolong the lifespan of the electrolytic caps.

These are the culprits… a last look before they go into the bin. Board is working good as new. Let’s see how long the repair will last.

Various

EMI Sniffer/Checker

2015/12/30 Simon Leave a comment

Many designs have been published in the past for various EMI probes. All have there merrits for particular applications. Here, a very handy small probe, especially suited to check enclosures of switch mode power supplies and similar circuits for EMI leaks. The probe has particular advantages for localizing the actual leakage spots, because it only captures fields in its close proximity, unlike many other EMI test probes.

The setup is very low-cost, using the venerable LM386 amplifier to directly drive a small speaker. Gain is set to 200, 46 dB. Sure, you can also hook this up to an oscilloscope, or to the line-in of a soundcard for waveform/spectrum analysis.

A 9 V battery is used to power the thing.

The sense coil – a small ferrite rod, with a coil of about 150 turns, small-diameter copper wire.

To protect the coil, seal it with some heat shrink tubing.

Happy EMI sensing!

Various

Ultrasonic Pest Chaser: final design

2015/12/30 Simon 2 Comments

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.

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.

The speakers are 2x KEMO L010,

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).

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.

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).

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.

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

Final testing…

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.

Various

Vintage Transistors and IC Stock: listing

2015/12/24 Simon 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

2015/12/04 Simon Leave a comment

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 Datasheet

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

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.

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:

… 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.

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).

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.

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….

2015/11/30 Simon Leave a comment

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!!

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).

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.

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

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.

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!

This is the microprocessor code, avrgcc.

marder1_151130

Various

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

2015/11/27 Simon 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.

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

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

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:

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).

SimonsDialogs

Category Archives: Various

A13 30 MHz Reference Oscillator: a reasonably quiet oscillator, and a noise cable

440 MHz ISM Band Amplifier: a few extra milliwatts….

Vintage IC Stock: listing

IBM Thinkcentre M50 P4 3 GHz: electrolytic capacitor repair

EMI Sniffer/Checker

Ultrasonic Pest Chaser: final design

Vintage Transistors and IC Stock: listing

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

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

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

SimonsDialogs – A wild collection of random thoughts, observations and learnings. Presented by Simon.