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  1. AnalogKid

    And the Relay is Called ...

    You are right about the 11 pin base industrial control relays. There are tons of time delay relays and timer modules on ebay. ak
  2. AnalogKid

    Need help on circuit.

    Your question is very poor and needs much more detail. What is the intent of the original circuit? If the idea is that pressing SW2 turns on the relay and pressing SW1 turns off the relay. If this is what you want, this circuit will not do it for you. As mentioned above, the voltage on...
  3. AnalogKid

    P=I*R

    One equation is Joule's Law. The other is Watt's Law. Although they were developed independently and for different reasons, one transforms into the other using Ohm's Law. The third permutation is P = E^2/R. You can use which ever one suits the information you have available. ak
  4. AnalogKid

    High Low logic

    Yes. In a floating regulator like the LM317, the voltage source that powers the internal regulator circuit is the input-output differential voltage. That is why it has a minimum value that is over 1 V. An LDO can have a Vdiff of much less than 1 V, and less than one Vbe drop. That is too...
  5. AnalogKid

    24VDC Relay Driver switching 240VAC 10A Load

    The standard rule of thumb for electronic components (overrate everything by 100%) applies in part to an SSR. For a 10 A output current, use a 20 A part. You do not have to overrate the voltage spec, because an SSR with a max output rating of 240 Vac is designed to handle that continuously. ak
  6. AnalogKid

    Diode and Capacitor Question for motor connection

    The primary job of a schematic is to show the electrical connections, not the placement of components. The two decoupling capacitors should be as close as possible to the IC power and ground pins. ak
  7. AnalogKid

    Sensor circuit

    That is disgustingly cheap. I can't even think about a circuit for less than that. Nice find. ak
  8. AnalogKid

    Sensor circuit

    Why? Indoor? Outdoor? 20 mA? 1000 amps? Power available for the sensor circuit? Latch off the power when the temperature exceeds the trip point? Reconnect power when the temperature decreases? Common ground? Isolation between the sensor circuit ground and the 220 Vdc ground? Source of the 220...
  9. AnalogKid

    Windmill vane controller

    When you say "vane", are you talking about the blades? Are you trying to change the pitch of the blades to optimize power transfer? Plus, feather them in times of high wind? This is different from turning the entire windmill to face the wind. for that, you do not need to know the wind speed. ak
  10. AnalogKid

    Dual Cycle Flip Flop Timer

    Also, what controls the winch? Does it have a mechanical gearbox for reversing, do you reverse the power connections to the motor, does it have an electronic controller, or or or? There are many ways to make a timer circuit that has an output that is in one state for 4 seconds, then another...
  11. AnalogKid

    Help with a flashbulb project

    The source for charging the capacitors isn't the batteries directly. The batteries power a small switching power supply, often based on a "blocking oscillator", that chops the batteries' DC into a form of AC and run it through a transformer to step it up to a voltage high enough to sustain an...
  12. AnalogKid

    Transistor gate voltage

    The idea is to control a very large current with a much smaller current through a much smaller switch. A 100 A - 200 A contactor is far more expensive and less reliable than a suitably rated power transistor.
  13. AnalogKid

    Transistor gate voltage

    No. Yes. No. Both battery negative terminals and the n-channel MOSFET *source* are tied together as the system ground. The drain goes to the rheostat, which goes to the +12. Add a 10K resistor from the FET gate to source so it turns off crisply when the +9 V is removed. ak
  14. AnalogKid

    Noob question regarding 555-DPDT relay-Motor

    If the motor current is low enough, then two CMOS 555s can form an H-bridge and drive the motor directly, eliminating the battery power wasted in the relay coil. ak
  15. AnalogKid

    Transistor gate voltage

    Not in this case. Having a separate voltage source for the transistor base ensures that the base current does not fluctuate if the 12 V source being tested sags under load. Also - IF you want the transistor to act as a switch rather than as a constant current source - the rheostat should be...
  16. AnalogKid

    Transistor gate voltage

    Your drawing has two wires going to what I think you mean to be the base of a bipolar transistor (not a FET). Also, there is no connection between the base circuit and the emitter, so it looks like nothing will happen. In your post, you don't say what it is you want the circuit to do. If you...
  17. AnalogKid

    Video rotation

    So, what is the answer? ak
  18. AnalogKid

    Night detector power LED (with LDR)

    TIP30 or TIP32. Add a 220 ohm resistor in series with the base before the pot wiper. This prevents blowing the base-emitter junction with too much base current when the pot is turned to zero. Note that the LED will not snap on crisply; it will wander up as the ambient light decreases. For...
  19. AnalogKid

    Help with a flashbulb project

    If you go on ebay, you will find many RF remote control transmitter/receiver pairs that have a relay for the receiver output device. Connecting the normally-open relay contacts across the existing switch should be all that is needed. ak
  20. AnalogKid

    Circuit board wire connectors question

    Not as easily as you might think. That is not ribbon cable, it is a flex circuit. And there are no connectors; both ends are soldered directly to the pc boards. Note that those are at least 2-layer, if not multi-layer pc boards, so unsoldering the wires is delicate work. Too much heat and...
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