Search results

Search Forums New Posts
  1. KJ6EAD

    Ceramin Cap Label question

    You are wrong by a factor of 10,000 on the capacitance. 102 is 1000pF or 1nF (preferred nomenclature) or .001μF. You got the tolerance right. Don't forget the voltage rating. Ceramic capacitors rarely fail. I think the most common failure mode is mechanical (a broken lead) which would be an...
  2. KJ6EAD

    Sound Sensitive LED Sequencer

    Shouldn't you be using a low pass filter if you want to track the beat?
  3. KJ6EAD

    Variable frequency sound emitter

    There are many ways to do it. I might try to use two 556 dual timers or even a single 558 quad timer. That would give a total of four timers. The first timer would be configured as a monostable to set the duration of the sound by enabling/disabling the second timer which would alternately...
  4. KJ6EAD

    What is this?

    The components suggest some kind of test interface that would cycle through the connected lines injecting a signal and measuring the return via an attached voltmeter, possibly just a cable tester. OP227 - dual instrumentation amp X2 LF356 - JFET op amp DAC0800 - 8-bit DAC X2 74193 - 4-bit...
  5. KJ6EAD

    What is this?

    It's custom built as indicated by the wire wrap and hand labeling. If I could see the components on the wire wrap board I might get an idea.
  6. KJ6EAD

    Help identifying blue capacitor in power board of espresso maker

    Voltage, physical size & lead spacing and energy rating in that order will be the considerations for a replacement. No, color was not included, but if you want blue, try Bourns. The one you had appears to be a 10mm disk but if you have room and the lead spacing matches you can get a higher...
  7. KJ6EAD

    Help identifying blue capacitor in power board of espresso maker

    It's not a capacitor. It's a MOV (metal oxide varistor) TVS (transient voltage suppressor) intended to absorb surges but not ones that big. The odds that it's the only component that needs to be replaced are less than even. In any case, you need to thoroughly clean the remaining soot off the...
  8. KJ6EAD

    Electrolyte Testing for Homemade Batteries

    Beware that mixing acids with bases can create strongly exothermic reactions which may expel the liquids forcefully from their containers and bases such as your wood ash soluton will react with aluminum to form explosive hydrogen gas.
  9. KJ6EAD

    Electrolyte Testing for Homemade Batteries

    I just skimmed it. I knew it had some errors like referring to a sodium hydroxide solution as an acid but I didn't see the ones you mentioned. It has the look and feel of student/intern research with the attendant false assumptions and erroneous conclusions but it's otherwise fairly comprehensive.
  10. KJ6EAD

    Young jedi needs pcb/switch type assistance!

    That switch is made for PCB mounting. Did you plan to mount it on a piece of perf or pad-per-hole prototyping board cut to fit the housing? It might be made more stable that way.
  11. KJ6EAD

    Home Made Batteries

    http://en.m.wikipedia.org/wiki/Standard_electrode_potential_(data_page)
  12. KJ6EAD

    Electrolyte Testing for Homemade Batteries

    http://www.arizonaenergy.org/AltEnergyClub/homemade%20batteries.pdf
  13. KJ6EAD

    Buying wide range values of resistor pack from ebay

    http://www.vellemanusa.com/products/view/?id=500317 This is an E12 set of 10 each so get 2 wherever you can get the best price. I picked them up at Fry's. I keep looking for an E24 set but haven't found one yet.
  14. KJ6EAD

    Buying wide range values of resistor pack from ebay

    You're still only getting 50 values. I can get an E12 set (61 values, 10 each) for $7 retail.
  15. KJ6EAD

    Home Made Batteries

    Often, tap water contains sufficient impurities such as carbonates, sulfides and metal salts to be an effective electrolyte. Try running the experiment again with deionized or distilled water after cleaning all materials with the same water (wear rubber gloves to avoid contamination). It's also...
  16. KJ6EAD

    Fluke 87 meter learning how to use it

    To his credit and surprisingly, Danny posted that link in his opening post.
  17. KJ6EAD

    Help with a synth repair/power supply fault

    In that case, close visual inspection giving particular scrutiny to any high mass components such as transformers and large capacitors is in order as well as areas of the board(s) near mounting bosses, fasteners and case penetrations.
  18. KJ6EAD

    Buying wide range values of resistor pack from ebay

    I'd get a full E24 set (168 values) from 1Ω through 9.1M.
  19. KJ6EAD

    Help with a synth repair/power supply fault

    That manual is pretty low resolution so I'll just offer a few general hints. First, be sure your supply works, then the connector, then any fuses. If your supply voltage is present past that point, I'll be slightly surprised. If not, you should measure the current being sucked out of the supply...
  20. KJ6EAD

    Fluke 87 meter learning how to use it

    With my posts you have to keep checking because I'll put something up quickly before vB logs me out :mad: and then repeatedly edit for quite some time thereafter.
Top