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  1. AnalogKid

    Extremely fast on delay timers?

    7 ms probably is too short for an electromechanical relay to reproduce reliably, but very easy for a solid state circuit. How is it that you have this as a homework problem, but don't know about (let alone how to look up) the equation for R-C networks? What is the course you are in, and what...
  2. AnalogKid

    Terminals and Connector Sizes

    The barrel size is determined by the wire, and the wire size is determined by the current (or, for a line cord to a relatively small power supply, whatever line cord wire gauge you have). Separate from that, the fork/ring dimension is whatever will fit. ak
  3. AnalogKid

    Terminals and Connector Sizes

    I was about to suggest a fork terminal, and T beat me to it. His image is one with the ends turned up.. These work best on terminal blocks that do not have a floating plate under the screw head; the turned up ends hook behind the screw head. With the plate, an all-flat terminal works better...
  4. AnalogKid

    One of my colleagues...

    Seriously impressive guy ...
  5. AnalogKid

    Need help understanding this circuit (Mixing board meter bridge)

    U1A and U1B form a set-reset flipflop. It is forced into one state at power on by R2-C1. To change which state that is, you can change either the inputs or outputs. Let's Go with the outputs. The two outputs are pins 3 and 4. Disconnect the left side of R12 from pin4/R4/C3. Leave...
  6. AnalogKid

    Question on reversing polarity for DC Motors

    The way I read #1, the motor is controlled by a timer (or two) and the timer(s) are controlled by the switch. No center-off position needed. ak
  7. AnalogKid

    Once a minute chirp...

    Beat me to it. If you look up a unijunction transistor, sometimes you will see an equivalent circuit using two conventional transistors. Either one will do what you want once you deal with that whole offline power regulation thing. https://en.wikipedia.org/wiki/Unijunction_transistor...
  8. AnalogKid

    Pioneer SX 850 Receiver

    My old Pioneer gear of approx. the same vintage has a speaker disconnect relay to prevent pops at turn on, turn off, and output stage overcurrent. Could be a bad relay or relay driver. ak
  9. AnalogKid

    Trying to make a LDR circuit work ?

    ***Probably*** ? ? ? That's an interesting conclusion. The only part handling high voltage or current is safety certified in the US, Canada, and Germany. The bottom side layout clearly conforms to UL60950 creepage and clearance distance rules, complete with internal router cuts. And on my...
  10. AnalogKid

    Trying to make a LDR circuit work ?

    Please post a link to the part. ak
  11. AnalogKid

    digital timer that can be set to a minimum of six different times

    For my wife's pills, I have a five-alarm timer (only) I picked up on ebay for around $3. The display is plenty large enough, but programming it is quirky; the instructions were exceptionally poor and I just played with it until I figured it out. I know of nothing that fits all, or even most of...
  12. AnalogKid

    Trying to make a LDR circuit work ?

    Look for solar powered yard lights, path lights, etc. Very low cost, and does exactly what you want. For indoor lighting you would have to disassemble them, mount the solar cell outside, and connect the two with wires. ak
  13. AnalogKid

    Trying to make a LDR circuit work ?

    As above, two basic questions: 1. What is the LDR resistance under *typical* daytime conditions? 2. What is the LDR resistance under *typical* night time conditions? ak
  14. AnalogKid

    Hight input impedance DC buffer ?

    As long as you are taking your output from the emitter, adding *reasonable* resistance (not 1 ohm, not 1 Meg) to the collector leg will not affect the output. It does shift some heat from the transistor to the resistor. Note that your circuit has a *very* asymmetrical output impedance...
  15. AnalogKid

    Series Parallel Problem

    steve - in this forum is it ok to suggest a theorem by name without giving away the details?
  16. AnalogKid

    Analog guitar amp with digital meter

    Modifying the hour meter you have is not possible. Under the LCD is a small microcontroller that does the counting and display management. There are no unpopulated pads that might be an in-circuit programming port, so even if you had the original program code to modify, you couldn't reprogram...
  17. AnalogKid

    Audio limiter to quiet loud radio commercials

    Not hairbrained at all. But it's activation is based on the peak value of the waveform, which already is controlled at the signal source. The circuit technique is very common (Maxim has a microphone preamp chip with it built-in), but adjusting it to the sweet spot between the two types of...
  18. AnalogKid

    Timer circuit help

    I'm almost positive this will do the job, but deciphering the instructions is up to you: https://www.ebay.com/itm/12V-DC-Multifunction-Self-lock-Relay-PLC-Cycle-Timer-Module-Delay-Time-Switch-NJ/252170243910?epid=1544705664&hash=item3ab6848f46:g:KTQAAOSwLzdWRpo1:rk:1:pf:0 Here is another...
  19. AnalogKid

    Timer circuit help

    5 minutes is a loooong time for a R-C timer circuit such as a 555. Better to go with an oscillator/divider or a microcontroller such as a PIC. If you want to buy rather than build, there are several programmable timers on ebay with a relay output. Does the timer circuit or device have to run...
  20. AnalogKid

    Audio limiter to quiet loud radio commercials

    Are you sure the commercials are louder? Not apparently louder, but Vpp louder? The audio for commercials is more heavily compressed, which increases the perceived loudness and "punch" without increasing the voltage peaks. In other words, the peak to peak value is the same as pre-compression...
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