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  1. (*steve*)

    Kenwood oscilloscopes?

    I've not owned or used a Kenwood oscilloscope. Does anyone have anything to say about their build quality or failure rate in their old age? Or maybe experience in their repair... are they made of unobtainium? "Kenwood" was the name of a very cheap "hi-fi" brand here, and I've consequently...
  2. (*steve*)

    Dissipating energy stored in an inductor

    I'm toying with designing a device for measuring inductor saturation currents. There's plenty of these on the web, but I have a need to go up to 30A and (at lower currents) up to 1H or thereabouts. At moderate currents and inductances, there's not a lot of problems dissipating the energy...
  3. (*steve*)

    Woke up this morning

    And look what I saw. It was a bit cloudy.
  4. (*steve*)

    Making a variable power supply variable... (what?)

    OK, weird title. What I want to do is to make a variable power supply controllable by a microcontroller. This is a switching (DC-DC) power supply, and the generic circuit is as follows: See the datasheet here. The Adj pin feeds into a comparator which compares the voltage on this pin to...
  5. (*steve*)

    Tin plating

    I've been mucking about with diy tin plating and here are my latest results. I mixed up enough solution to about half full this beaker. Measuring 0.025g of one of the reagents was probably the hardest bit. And here are the results The playing on the left was a result of a few minutes...
  6. (*steve*)

    EG&G PAR 5210 Lock-in amplifier repair

    Ok, no guessing games this time. It's a Princeton Applied Research model 5210 Lock-in amplifier. Coming from the same source (a calibration and repair facility) so I'll assume it's BER even though the description didn't say so. (If it's not, I'll sadly move this thread somewhere else)...
  7. (*steve*)

    Tektronix TDS3054 data acquisition failure

    Look what I've been asked to fix now: There's a few teardowns on YouTube (Dave Jones tried to fix a fault on one of these). Bugger all documentation, and only a few voltages C/- Dave, so I'm not hopeful. Everything after the data acquisition seems ok (not sure if that includes the memory)...
  8. (*steve*)

    Successful Stanford Research SR530 lock-in amplifier repair

    Here is a new toy I received today... With a 3.5 inch hard drive, a small dog, and a large cat for scale. Doesn't look like the packaging is damaged. What is it? Will I need to repair it?
  9. (*steve*)

    You know you're a valued customer when...

    You get a huge "Cust Level Discount" Woo Hoo! :-D I wanted a single 74HC259. Can I get one? Noooooooo Would you order 10, or 25? Both in stock (tick) Both for delivery in 5 working days (tick) So now they're going to be dispatched on the 6th working day. I wonder if they're...
  10. (*steve*)

    +15V supply shorted

    I have a power supply which generates a +/- 15V rail. The -15V is fine, while the +15V measures around 50mV. The 7815 gets very hot. I suspect it's a short :-) Unfortunately, the PSU is on a fairly large board, and I can't disconnect it from the rest of the board. I've tried my calibrated...
  11. (*steve*)

    Phantom powered preamp

    I'm after a preamp which runs from phantom power. I have 2 microphones, one of which requires phantom power, the other which won't work with phantom power turned on. The mixer turns on and off phantom power simultaneously for all mic inputs :) The microphone which doesn't like phantom power...
  12. (*steve*)

    Hey, are you in Brizzie?

    If you're a banana bender (or live amongst them) and your calender isn't choc a block on wed 3/5 in the late arvo, come and have a coldie with me! I'll be staying near the state library and I have one night free.
  13. (*steve*)

    Talking to my phone

    Hi this is an example of me trying to talk to my phone and getting it to type my message instead of me having to type the bloody thing on the little tiny keyboard. Amazingly enough this entire message has been written without me having to type a single thing is actually pretty impressive...
  14. (*steve*)

    DMCA weirdness

    I am writing some code to edit and convert gerber files into a useful format. (If the bloody software won't do what I want, then I'll fix it myself!) Google for "The gerber file format specification" and you find that there's a DMCA complaint removing something (that's strange). Investigate...
  15. (*steve*)

    Holiday pics

    As several of you are aware, I had a small holiday at the beginning of this month. What follows are some highly political images taken during that holiday... And now some that are less challenging for parts of our international audience... And some random...
  16. (*steve*)

    What is up with this?

    In a post in the homework section, @hevans1944 says: I thought I would follow the advice to the op, but quickly found myself wondering... On the bottom of the first column on page 4, when discussing the choice of mosfet for the circuit in figure 5 in the second column of page 3, they say...
  17. (*steve*)

    What's this called (knob attachment)

    I have some smashed knobs with the following type of attachment. What's that method of attachment called? I want to try to search for some similar knobs...
  18. (*steve*)

    Dial cord slipping

    I have a piece of equipment that has a dial cord. The cord is wrapped twice around a 1/4 in diameter brass rod which is the shaft for the knob on the front panel. In one position the dial cord slips leading me to turn the knob more until the resistance is overcome and the main control starts...
  19. (*steve*)

    Transformer primaries in series, secondaries in parallel -- ok?

    I am after a transformer with a 15-0-15 secondary at several amps. Yesterday a couple of transformers landed on my lap (luckily they didn't land on my foot). Unfortunately they each have a pair of 30V windings. Can I connect the primaries in series and the outputs of the two transformers in...
  20. (*steve*)

    Can anyone ID this transformer?

    I have two of these transformers and I'm after some further information if anyone has anything. The high voltage secondary is marked as 250-0-250 and 60mA DC. There are three other secondary windings, 0-4-6.3 2A, 0-4-6.3 3A, and 0-4-5 3A. I'm curious about how to understand the rating...
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