Search results

  1. (*steve*)

    Hour meter for laser cutter

    At the hackerspace I frequent we have a couple of laser cutters. We want to keep track of the laser time to track tube life. Someone got inside and found a signal that is about 4V when the laser is off, and 0V when it's on. Some more investigation revealed that it can't sink or source much...
  2. (*steve*)

    MAX883C/D (Just because!)

    I have absolutely no use for these, but they were cheap and I wanted to look at them. Introducing the MAX833C/D. It's nothing really special, just a Low quiescent current, low dropout regulator. They come, 100 at a time in a little box like this: When you open it, it looks like this: What...
  3. (*steve*)

    Newark / Farnell / Element 14 become my new "supplier of last resort"

    I'm looking for a Keithley 6172 triax adapter. It's not common, probably due to the fact that it has always been a specialty part, and never in great demand. Most of the larger suppliers have them listed as out of stock or obsolete, but I found them listed on Element14's web site with an...
  4. (*steve*)

    ETI magazine Feb 1979 - power supply (ETI-142)

    Someone has dumped an ETI 712 power supply (I think) at my local hackerspace. Edit: it's an ETI-142 Does anyone have a copy of the magazine article(s) which describe it? Our state reference library may have it, but they note that this particular year is incomplete without giving details. The...
  5. (*steve*)

    I thought I'd measure the leakage current of a few caps

    After measuring the leakage in some diodes, I thought I'd measure the leakage in some caps. I have some nice (we'll find out how nice) 330pF polystyrene capacitors, and for comparison an X rated 3n3 capacitor. The 330pF capacitor measures 1.95x10-13A, that's 195fA with about 12.8V across it...
  6. (*steve*)

    I just thought I'd measure a few diodes V vs I

    Did you ever wonder what V vs I looks like for diodes for very low forward (and reverse) voltages? Well I decided to run some tests today, partially to see how low I could go before noise got in the way. At present I don't have a shielded enclosure etc, so all of this was done with banana...
  7. (*steve*)

    How sweet it is to be an idiot

    I have just deleted a massive post and banned the author. It basically went into great detail about how moon landings are impossible and that they were faked. Although I didn't read all of it, I think the arguments suggested that all spaceflight was impossible (including unmanned spaceflight)...
  8. (*steve*)

    What's so special about mini-MELF 1N914s?

    OK, a surface mount 1N914 is a pretty cheap "jelly-bean" component, right? Well, check out the price in the DO213-AA package! Also here. Why so expensive?
  9. (*steve*)

    Health Care is so damn expensive...

    Can I take the time to complain? First, let me say that I'm late in my working career and health Care is probably about as expensive as it's going to get for me. I (and my wife) have a number of conditions, and we fall outside any income, employment, or age related criteria which would lessen...
  10. (*steve*)

    Resistors, Capacitors, Zener diodes... Why the funny values?

    (*steve*) submitted a new resource: Resistors, Capacitors, Zener diodes... Why the funny values? - An explanation of the E-series and why those funny values are used. Read more about this resource...
  11. (*steve*)

    74HC oscillator, how fast?

    Using bog standard 74HC series logic, what is the fastest oscillator you can make?
  12. (*steve*)

    Mosfets and second(ary) breakdown

    A note to those who already know this... I've just learned this and I thought it was interesting enough to post -- I'm not claiming to have discovered it! A common statement is that "mosfets are not subject to secondary breakdown". It's one I've made multiple times and is one that appears in...
  13. (*steve*)

    100G ohm resistor only measures 50G ohm

    I got my brand new 100G ohm resistor (it's sealed in an evacuated glass envelope) and it measures only 50G Ohm!!! What could be the problem? If I disconnect the coax with the alligator clips on the end, it measures (open circuit) 100G ohm. If I disconnect the coax, it measures something in...
  14. (*steve*)

    Tektronix 577 curve tracer

    I have finally pulled out my Tektronix 577. It arrived with a few screws lose inside it, and the cover on one side has been removed and replaced incorrectly. Not a good sign. It turns out that the top and bottom section (the top section contains the CRT) were separated at the back and those...
  15. (*steve*)

    Fixing an HP3455A multimeter

    Some of you may be aware of my huge stash of test equipment bought for a song and transported half way around the world at great expense... Well, among that stash is a couple of HP3455A multimeters. Because I had 2 of them I decided to take one down to my local hackerspace to equip them with a...
  16. (*steve*)

    Keithley 600B input mosfets

    I started fixing up a Keithley 600B electrometer over the weekend. The problem I'm having at the moment is that the input stage is rather suspect. The device is essentially an OP-AMP made with discrete components. It allows measurement of extremely low currents, and very high resistances...
  17. (*steve*)

    PM 5192 ressurection

    I have a PM 5192 programmable synthesizer/function generator (0.1mHz - 20MHz). This is very similar to the PM 5193 except the latter goes all the way up to 50MHz. Mine is labeled as being a 100VAC unit, with a sticker saying 120VAC. Looking at the manual there is a different set of taps for...
  18. (*steve*)

    Merry Christmas

    A happy Christmas, Saturnalia, Hanukkah, or whatever else you may be celebrating!
  19. (*steve*)

    Woo Hoo HP5316A

    I've spent some time getting my HP5316A and HP5334B working. (They are both 2 channel counters AKA frequency meters). I am using my GPS 10MHz signal source as a reference. With a bit of tweaking the HP6316A's clock can be adjusted to within a few tenths of a Hz from the GPS, but it drifts a...
  20. (*steve*)

    Hey, anyone want something they can take into space?

    Check this out.
Top