Search results

Search Forums New Posts
  1. CDRIVE

    MOSFET IRF540A circuit.

    Justin, how would you like to do a Picaxe test for me. I want to confirm some Data Sheet specs of the Microchip itself. Chris
  2. CDRIVE

    Tucker

    This conversation is beginning to remind me of lunch break at my work place before retiring. I was a Bio-Med Electronics contractor at a local hospital for about 14 years. Lunch time was a real treat and I'd sit with friends from the Engineering dept. George T. works in the Bed Shop and...
  3. CDRIVE

    Problems substituting a relay

    Huh? Think about what you just said. How can there be nothing wrong with this circuit when you're telling Paul that he has to make a page full of modifications to make it work properly? With all do respect, I stand by my opinion. Properly designed circuits don't require re-engineering by the...
  4. CDRIVE

    Problems substituting a relay

    Paul, I Spiced your original circuit with a 1.2KΩ coil and it's no wonder that the contacts fried. I suspect that even with an exact relay replacement they're going to keep frying. I would love to know what the EE that designed it was thinking, besides cost savings. It's an awful design and not...
  5. CDRIVE

    Problems substituting a relay

    Ha, Good eye gorgon! I never even questioned that statement. It doesn't compute. It's still a crappy power supply design though. ;)
  6. CDRIVE

    Problems substituting a relay

    Start checking the other components on that board. Pay particular attention to the 1uF and 220uF Cap. Something isn't right here. The base current to saturate that transistor should not load your circuit. What's the value of the base R? Chris
  7. CDRIVE

    Problems substituting a relay

    The 1uF Cap in your circuit is the primary component that interfaces your 240VAC and limits the current to your board. Are you in the UK? That design would never be approved on this side of the pond. A step down isolation transformer would be mandatory code. That aside, once the transistor...
  8. CDRIVE

    Problems substituting a relay

    OK, I understand now but it shouldn't be wired like that. The LED should be across the coil with a limiting resistor in series with the LED. The LED shouldn't be in the coil current leg.
  9. CDRIVE

    Problems substituting a relay

    That's an oddball circuit. Why are there two LEDs that will be lit simultaneously? I suggest that you half the value of the resistor. Edit: I just want to be clear on this. Your relay problem is effected by the ORG LED and resistor in series with the coil. Why is it there when you have...
  10. CDRIVE

    Low Pass filter doesnt work ?

    Not surprising. A big cap like that swamps out your PWM. You should be using bypass/decoupling techniques on your power rail to the uC. I'm assuming that you mean electrical noise and not audible. On the other hand, if it's audible hum that's offensive, a small cap like .1uF across the motor...
  11. CDRIVE

    Resister in series to decrease wattage

    The guy probably replaced it with a solar heater by now. :D
  12. CDRIVE

    Digital Pot setup

    Keep me posted. Chris
  13. CDRIVE

    need a max232 connection to a DB 9pin

    :eek: Is that one sentence?
  14. CDRIVE

    Building a 49.8 MHz receiver

    Reverse engineering is not as easy as you may think. Can you post a good photo?
  15. CDRIVE

    Power Supply refuses to Power Coil

    No, the power supply needs to see a resistive load, which is what it sees after initial settling time after power is applied to your load. Wind enough wire on there to produce a DC current not greater than your supply can handle. If it's a light duty supply you're going to need small gauge wire...
  16. CDRIVE

    Digital Pot setup

    The OpAmp will then have a gain of 2.2. Can you live with that? Chris
  17. CDRIVE

    Correct way of converting 12v down to 3.3 for a pin input?

    If that's the case and you want a full voltage swing from 3.3V to near zero V you can move the emitter resistor to the collector and ground the emitter. The 3N33 is a Darlington, so the collector will never go far below ~ .7V but other model optos are not Darlingtons. Non Darlington models can...
  18. CDRIVE

    PWM modulation on a AM transmitter

    Tittle of this is making any sense to me. In one breath you're talking AM, in another it's PWM. They're not the same. The bottom scope pattern that you posted depict an amplitude (Audio Wave) modulated carrier, while the top pattern is PWM, that's more akin to FM or FSK. Yet the bottom trace...
  19. CDRIVE

    Correct way of converting 12v down to 3.3 for a pin input?

    No, it's not overkill. The 'Isolation' breakdown voltage is very high for all OptoIsolators and, as stated by Gorgon, has little to do with your particular circuit, which has no voltages, on either side of the Opto, that are that high. Regarding switching speed or frequency response.. This...
  20. CDRIVE

    Tucker

    Ah, got it. Roger that.
Top