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  1. AnalogKid

    Need circuit for one or two IR led illuminator

    Datasheet for the LED's? Datasheet for the photocell? This can be done with two transistors, or one opamp plus a driver transistor, or one logic gate plus a driver transistor. Which approach best fits your available parts and your skill set? ak
  2. AnalogKid

    electrical delay line attempt

    Ampex pioneered videotape timebase error correction (AMTEC) and color phase error correction (COLORTEC). Both used voltage-variable video delay lines - a long tapped inductor with varicap diodes at each tap. In resurrecting an old meatball TR-22, I made them by hand-winding the inductor on a...
  3. AnalogKid

    electrical delay line attempt

    Transistors that can switch at terahertz frequencies are very rare and very expensive. Nowhere in this thread do you say what it is you want to achieve. What is the source of the signal you are delaying? How much delay time do you need? What is the destination for the delayed signal; what...
  4. AnalogKid

    Taking Requests

    Easy: Sweet Child o' Mine Hard: The Spirit Of Radio
  5. AnalogKid

    new original voltage doubler circuit

    I think I know. The first cap charges almost instantly, as there is no series resistance: V+ > diode > cap > diode > V-. The next cap charges through a (top secret value) resistor, so the upper diode's anode voltage increases much more slowly. The third cap doesn't start charging until the...
  6. AnalogKid

    new original voltage doubler circuit

    Very low efficiency - way too many resistors. AND - it won't work. Add reference designators to *each* component and values to each resistor, and I'll explain why. ak
  7. AnalogKid

    True flash ADC

    Note that the schematic in post #3 will not produce the image in post #3. The schematic has no retention - as the 4017 steps through the columns, as one LED in a column lights, the LED in the previous column goes out. You will see a moving dot, not a line draw. If the writing rate is fast...
  8. AnalogKid

    Need help interpreting something on a schematic

    Reworking the Proco circuit for a 4558 is not at all difficult. What is your intended power source(s)? ak
  9. AnalogKid

    Need help interpreting something on a schematic

    This is an overdrive distortion circuit. It drives a linear amplifier into clipping intentionally, a form of a "fuzz box". As above, the 150K part is a pot. It adjusts the amount of overdrive distortion. The + input must have a resistor to GND to establish the operating point of the opamp...
  10. AnalogKid

    Reversing polarity through signal from mouse switch

    Here is a circuit from another question last December. For your use, the two switches (NO contacts) are wired in parallel in the place marked SW1. When either switch closes, the circuit reverses. The circuit is based on an impulse relay that performs the toggle and latch functions. This link...
  11. AnalogKid

    Reversing polarity through signal from mouse switch

    They are SPST (NO) or SPDT limit switches. ak
  12. AnalogKid

    Reversing polarity through signal from mouse switch

    What you have are essential pieces, but not everything that is needed. The two switches control whatever is doing the actual voltage reversal. One way or another, the basic method is a toggle function and a DPDT power switch function. These can be done with all relays, all electronic...
  13. AnalogKid

    Reverse Day/Night

    What is the operating current or power for the pump motor? It should be on the label. ak
  14. AnalogKid

    Op Amp assortment

    For the same circuit topology, clipping percentage, etc., I prefer the germanium sound over silicon. Made both for a cousin for an A-B test - clear tonal difference. ak
  15. AnalogKid

    Op Amp assortment

    Guitar pedal people love the 741, and really love the even older 301 and 308. From a pure audio performance view, none of these are good. But a guitar pedal is not about pure, clean audio, and the coloration these parts add to the signal is considered classic. Some pedals from the 60's fetch...
  16. AnalogKid

    What is this switch type? It’s driving me crazy!

    In the audio world, stepped attenuators are considered much more accurate, professional, and classy than a standard smooth-action volume control. But they relatively expensive, so, or course, there is a way around that. The pot has a detent wheel just like some rotary encoders do, giving the...
  17. AnalogKid

    Transistor-triggered photogate

    What color is the LED?
  18. AnalogKid

    Transistor-triggered photogate

    Please describe the circuit's operation. Among other things, what is its "rest" condition and what is its "triggered" output? Is there anything physically between the LED and phototransistor? ak
  19. AnalogKid

    Rain gauge resetter

    Without seeing the electronics inside the sensor it is impossible to say for sure - BUT - there is a good chance that the sensor is sending some data rather than a simple RF burst. This would prevent the receiver from counting extraneous RF sources. ak
  20. AnalogKid

    Rain gauge resetter

    Yes. My read of post #1 was data loss due to battery change. Solution, fewer battery changes. I assume AC power is not available at the remote site ... ? ak
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