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  1. crutschow

    Simple Dual Op Triangle Generator Issues

    That would be good. :)
  2. crutschow

    Simple Dual Op Triangle Generator Issues

    That's bad form. It may help keep your head on straight, but it puts a kink in ours. Normally all voltages should be referenced to ground/common.
  3. crutschow

    Simple Dual Op Triangle Generator Issues

    You likely have a wiring error. Double check all the connections After that, if it's still now working, measure all the node voltages and show them on your schematic posted here. Why do you have the +P voltage to the op amp shown as 4.5V? It should be 9V.
  4. crutschow

    P-Channel LDO Voltage

    There is no op amp in the schematic you show, so what is the schematic using the LM358? Below is the simulation of a circuit similar to the one you posted but uses one less transistor. Not only does this reduce part count, but it reduces the feedback loop gain, thus it is less likely to oscillate.
  5. crutschow

    Low power cutoff not working

    You double check all the wiring and determine why the voltages are not correct, since you apparently have a wiring error.
  6. crutschow

    Low power cutoff not working

    Your REF voltage is way off. It should be 1.24V at the trip point. The pot setting should be adjusted until you get that voltage where you want the circuit to change states.
  7. crutschow

    Low power cutoff not working

    My simulation of the circuit works. What do you mean "the TLV431 does not allow the voltage to turn on the 2n2907"? What are all the circuit node voltages when that happens.
  8. crutschow

    Where to buy shielded jumper cables?

    Of course, you will now have two connections at each end of the cable that must be connected, as the shielding doesn't help if it's not grounded. Why do you think you need shielded cables?
  9. crutschow

    Low power cutoff not working

    Here's the sim with the TLV431 set for a trip point of around 3V:
  10. crutschow

    Low power cutoff not working

    Why are you operating at such a low voltage? I though you wanted it to trip around 3 to 3.5V? For such a low voltage the TL431 will not work, you might try the TLV431. which has a 1.24V reference.
  11. crutschow

    Low power cutoff not working

    Don't understand the reason for that unless the transistor bias is not correct, or you are still using a MOSFET. Post the exact circuit you have. Below is the LTspice simulation of the circuit using a P-BJT with the trip voltage set at 3.5V (green and red traces). R4 provides a small amount of...
  12. crutschow

    Low power cutoff not working

    I asked about the maximum load current since that affects the transistor base biasing to get the needed base current for a given load.
  13. crutschow

    Low power cutoff not working

    The load is still not connected to Vcc. There is not enough voltage to turn the MOSFET on and off, since the saturation voltage from the TL431 anode to ground is about 2V. It should work if you use a P-BJT instead of a MOSFET. What is the maximum output load current?
  14. crutschow

    is this bjt transistor hbridge right?

    No, the Arduino output by itself is not sufficient. Yes, you can "set em off" with a 30k resistor, but that's when the emitter is at ground potential. The base-resistor value is not a factor here, it's the base-emitter voltage that's critical not just the base voltage, so they won't "fire" from...
  15. crutschow

    is this bjt transistor hbridge right?

    You cannot control a 12V H-bridge directly from the Arduino. The top transistors need a driver to generate the 12V base control signal required.
  16. crutschow

    Using a relay to power a magnetic lock with a separate power supply

    The module you referenced should work fine. As you can see it's good for 10A@30Vdc. Should be no problem to power it directly from the 7A Autoslide's supply.
  17. crutschow

    4017 ?

    So what's the cheat, and how does it work?
  18. crutschow

    CMOS??

    No, the LM555 is the standard bipolar version. One CMOS version is the LMC555.
  19. crutschow

    4017 ?

    Don't see how that will work without additional circuitry(?).
  20. crutschow

    4017 ?

    You might be able to save a chip if you instead use three quad CD4019 AND/OR select gates instead of the CD4053 mux, but it does require both the 555 output and it's inverted output to control which input is selected, which may require an inversion gate.
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