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  1. CDRIVE

    Help need for amp. hum

    My guess is you're trying to say half "wave" not half "way" but then you say there are 2 Diodes. If there are 2 Diodes then the circuit should be using a center tapped transformer. If so it's not a half wave rectifier if wired properly. Chris
  2. CDRIVE

    Modifying pre made delay timer module

    That's not entirely accurate. Jumper (S5) will connect the + input of the Control Vcc source to the common (C) terminal of the control relay. This begs an answer to the question that Alec asked. Chris
  3. CDRIVE

    Modifying pre made delay timer module

    I found some more info Model FC-31 Chris
  4. CDRIVE

    Modifying pre made delay timer module

    Dave, there appears to be 4 jumper headers on his board and we don't know what they do or if any of them can change that logic. Chris
  5. CDRIVE

    Modifying pre made delay timer module

    I found it on Ebay 5V Power On Delay Module The time delay is variable from 100mS to 1Hr. so that can't be the issue. The control relay provides both NC/NO logic. So what's the question again ... stated differently? Chris Edit: Here's a 5-12V Delay Module that's far more descriptive
  6. CDRIVE

    Modifying pre made delay timer module

    At first glance the description and subsequent question seemed simple and clear. Unfortunately this is one of those post that should be read only once. This is because reviewing it does just the opposite of clarifying anything. Are you saying the maximum delay period isn't long enough or are you...
  7. CDRIVE

    Astable 555 Circuit Problem

    Also insure that the cap is correctly polarized. IE: Neg band is connected to (-) GND. Chris
  8. CDRIVE

    Basic Toggle Switch Circuit

    (1) Yes, they're all the same quad NAND Gate package. (2) Yes, they're mislabeled. Follow the attachment you posted. (3) No, the node marked +5V is an Output not an Input. Vdd (Pin14) of the 4093 gets tied there too. When your PC turns On the USB power pin (~5.5V) charges C1 through D1 and...
  9. CDRIVE

    Basic Toggle Switch Circuit

    Yes AK, that was my point. ;) Judging by your description here you perhaps saw a schematic of the chip (U3?) in question? If we can determine a single (control) node (anywhere on that board) that is held low when the amp is on and held high when the amp is off we may be able to facilitate a...
  10. CDRIVE

    Basic Toggle Switch Circuit

    I'm not sure what you're saying. ZSteve needs 5V pulse On & 5V pulse Off. I'm just saying it isn't going to happen with a single transistor and associated R & C. Perhaps you can draw it? Chris
  11. CDRIVE

    A means of closing a JFET switch with a postive voltage?

    Hey I'm an old fart! You'll get there someday (maybe?) and you'll find an hour ago, a day, 6days, maybe a month, all seem to run together with absolutely no discernible difference between them. Hell, I told my wife today that the Corn Beef Hash & Eggs she made for breakfast was great! She looked...
  12. CDRIVE

    A means of closing a JFET switch with a postive voltage?

    I probably missed or forgot it. It's been a long journey. :D I'm guessing that 1.5V offset is now acceptable to you. I know it wasn't at the beginning. Chris
  13. CDRIVE

    Basic Toggle Switch Circuit

    Much has been said here regarding a simple BJT switch paralleling the push button but he's going to need a bit more than that if shunting the switch is the rout he takes. As I see it zsteve needs the following logic.. (1) PC turns ON: 5V USB power is used to fwd bias the BJT ON 'momentarily'...
  14. CDRIVE

    A means of closing a JFET switch with a postive voltage?

    The TL074 will produce an output offset voltage ~1.5V when used with a single ended 9V power source. I told you waaaaay back (in which topic title I don't remember) that the first basic feature that your application needs is an OpAmp that sports Single Ended Supply operation. This information...
  15. CDRIVE

    Basic Toggle Switch Circuit

    There may be options other than toggling that switch. Do you have a DMM? Chris
  16. CDRIVE

    Basic Toggle Switch Circuit

    This is the "Technical???" specs on that board: :rolleyes: "Parameters: Size: 8.1CM * 3.2CM Supply voltage: 5V or 7-12V(When using a 5V power supply, short circuit to short-circuit the cap chease; When using the 7-12V power supply, short circuit to remove the cap chease) Control: Low pulse...
  17. CDRIVE

    A means of closing a JFET switch with a postive voltage?

    How can that be? 9V divided by 34 = ~ 265mV. Chris
  18. CDRIVE

    A means of closing a JFET switch with a postive voltage?

    I guess it's possible but highly improbable that this option wasn't proposed somewhere lost in this epic odyssey. Chris
  19. CDRIVE

    A means of closing a JFET switch with a postive voltage?

    Steve, keep a lot of coldies on hand. It's a long read if you go all the way back. I put links in this topic that will take you to beginning of this saga. Come to think of it you may want some tuck before you get through it all. :) Chris
  20. CDRIVE

    A means of closing a JFET switch with a postive voltage?

    That much I've got nailed down but the 9V source limitation with no overhead to play with is proving to be an exercise in futility. That plus lack of a negative supply rail, that many S&H circuits employ, makes this circuit a hard nut to crack. Chris
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