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  1. crutschow

    automatic forward reverse motor with limit switch and relay

    Seem a bit overkill for this application. ;)
  2. crutschow

    automatic forward reverse motor with limit switch and relay

    Here's my take on doing that: It uses two SPDT relays in a bridge configuration and connected as a FF latch. In operation, one relay will always be ON and the other OFF, with alternating action. To understand its operation, assume U2 is ON, U1 is OFF (12V on both sides of the U1 relay coil)...
  3. crutschow

    How change the Frequency of a 555 timer with another circuit ?

    Depends upon whether you are driving will emit noise from the pulses. Below is the circuit operating at 20kHz.
  4. crutschow

    How change the Frequency of a 555 timer with another circuit ?

    Yes and yes. At frequencies low enough so the comparator transition time is not a significant factor, the approximate frequency is F ≈ 0.345 / (R1*C1).
  5. crutschow

    How is current passing through the capacitor in the following schematic?

    Below is the LTspice simulation the circuit, to perhaps help clarify what has been said: The Q1 collector voltage (yellow trace) shows the waveform driving C1. The red trace shows the capacitor C1 current, which has a small, longer current pulse when Q1 goes high, and a higher, shorter current...
  6. crutschow

    How change the Frequency of a 555 timer with another circuit ?

    Not too involved. LTspice simulation below of an analog-control PWM circuit using one chip comparator (LM339/393), that goes from 0% (fully off) to 100% (fully on) duty cycle.
  7. crutschow

    Can't find the transformer I need so need to build my own

    Since roughly equal power goes through the primary and secondary windings, the primary wiring size also must be properly selected.
  8. crutschow

    How change the Frequency of a 555 timer with another circuit ?

    So you are changing the requirement from controlling the frequency to changing the duty-cycle of a fixed frequency. That's a big difference. Do you want to control the duty-cycle in steps by changing the values digitally, or do you want an analog continuous voltage control. If you want steps...
  9. crutschow

    Determine Sampling

    What is the maximum frequency rating of the accelerometer? I would sample at more that twice that frequency.
  10. crutschow

    How change the Frequency of a 555 timer with another circuit ?

    Is the 555 running as an astable oscillator? Do you care if the duty-cycle of the 555 output changes with frequency? How accurately does the frequency need to follow the control voltage? Or do you just want step changes in frequency?
  11. crutschow

    convert 110v dc to 110v Ac

    The difficulty is creating an AC sinewave, which the pumps may require to avoid overheating. You need to know the battery capacity and the motor power required to determine how long the batteries can power the pumps. Might be simpler to just buy a small AC generator. They aren't that...
  12. crutschow

    Solenoid Current Flow

    Did you also read that the time depends upon the value of the capacitance and inductance? 1µH is a very low inductance.
  13. crutschow

    Solenoid Current Flow

    Edit: That will allow the inductor current to reach the maximum current (red trace) where the capacitor voltage reaches zero and, at which point, the diode starts to carry the current, The current then decays to zero as determined by the resistive and diode losses from the current.
  14. crutschow

    Solenoid Current Flow

    Below is my LTspice simulation: The current (yellow trace) starts at zero since current can't instantly start in a inductor (you have to use the uic option in the transient simulation). It then rises to the resonant peak (here about 7.3A simulated) where the capacitance voltage (green trace) is...
  15. crutschow

    Need circuit for sine-to-square/sawtooth generator

    Are you referring to the 60Hz from a main's outlet? You will need to run that through a transformer for isolation. And I don't know of any "simple" circuit to convert that to a ±12V, 1A square to sawtooth signal.
  16. crutschow

    Voltage Drop after optocoupler.

    Where, exactly, are you measuring 0.6V? Do you mean the transistor base, or the input to the transistor base resistor?
  17. crutschow

    Voltage Drop after optocoupler.

    The base-emitter junction of a BJT looks like a forward biased diode, so the normal on voltage is just 0.6-0.7V.
  18. crutschow

    Reduce amperage without reducing voltage. Question. Help.

    The power supply current rating is just the maximum it can supply at its rated voltage. The actual current drawn from the supply is determined by the load. For example, you can hook a 1A bulb up to a battery that can supply 200A, but the bulb will only take 1A (assuming the bulb is rated to...
  19. crutschow

    unable to regulate baseboards

    Can you check the output voltages from the relays?
  20. crutschow

    unable to regulate baseboards

    Is any of the wiring aluminum?
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