Recent content by MrHeckles

  1. M

    Variable Power Supply

    Out of curiosity has anyone found any advantage in using a switching voltage regulator, rather than the LM317, for a variable power supply?
  2. M

    Highside mosfet gate spike

    I set the voltage difference pins on the gate and the source for the FET. Based on that I have moved the diode D6 to connect to the 12v supply, rather than the motor supply. That way it gives about +11 volts over the drain voltage to the highside gate (regardless of what the motor voltage...
  3. M

    Highside mosfet gate spike

    Thats exactly what should be happening. It's a fantastic braking method for the motor. It allows for very tight speed control. With the highside FET then turning back on, it gives very nice regenerative braking. The highside gate goes up to 22v or so, the spike is only around 14v-16v, just...
  4. M

    Highside mosfet gate spike

    Is there any good way to do that apart from sticking a larger resistor on the gate of the highside FET with an anti-parallel diode?
  5. M

    Highside mosfet gate spike

    I have used R13 and L2 as a basic simulation of a motor. M7 is supposed to remain on all the time. The PWM chopping for the speed control is done via M6. The motor is only supposed to drive one direction at this stage. M5 (I think this is other other lowside fet you are talking about)...
  6. M

    Highside mosfet gate spike

    Thanks Jim, I tried that, but it didnt seem to make any difference to the spike. I have sorted out some pictures. 1st, the circuit setup 2nd, the voltages from the probes in the first picture and a zoomed in view of the spike finally, this is a trace of the amperage through the highside...
  7. M

    Highside mosfet gate spike

    Hi guys. A while back I ask for, and received, a whole lot of help in regards to creating a motor controller. Happily it all worked out well in the end. I have recently decided to redesign the controller. Now I'm using pSpice to cut down on blowing up components. The circuit I have uses an...
  8. M

    SG3524 question

    One simple question about the SG3524 regulating PWM chip. The error amp inputs are pins 1 and 2, the output of the error amp (and the compensation) pin is pin 3. The current limit amp inputs are 4 and 5. The current limit amp will over ride the output of the error amp. My question is, if I...
  9. M

    Current limit delay

    Hi guys, I have a motor controller that uses the SG3524 chip to generate a PWM pulse. This is sent to mosfet drivers which run an H bridge setup. The onbard current limiting is resulting in a "jerkiness" of the motor when it starts to hit the 0.2v limit on the CL + pin of the SG3524. The...
  10. M

    any pinoy here pm me

    I have found the ICL7660 voltage converter chip to be very helpful. Here is a link to a datasheet for it. http://www.alldatasheet.com/datasheet-pdf/pdf/67436/INTERSIL/ICL7660.html
  11. M

    4PDT to SPDT trick

    Got it sorted now. I had changed the comparator to the -5v rail, and I figure that the -5v through the max333cpp was too close to V-. I changed it back to -9v for the comparator and it works fine. I also put in the reverse diodes to protect the transistors bases. Staigen - the -5v comes from a...
  12. M

    4PDT to SPDT trick

    I'll keep it in mind  :) But I had another idea. I changed PIN's 2 and 17 to connect to -5v, rather than ground. That way I figured it would drag the comparators + inputs to a negative voltage (and turn them off). However, it didnt seem to work. When I changed the switch, the LED's would...
  13. M

    4PDT to SPDT trick

    I have hooked the negative 9 volt rail to the MAX333CPP. The voltage on PIN 3 when it is supposidly grounding is now 0.08v. Lower, but not low enough to turn off the comparator. What is this other solution of yours?
  14. M

    4PDT to SPDT trick

    Its a bit hard to describe, so heres the setup As you can see, when the switch is open, and as long as there isnt to much voltage on the load signal feed, the forward comparator will latch on, turning on LED2. When the switch is closed, it SHOULD ground the forward comparator (thus turning...
  15. M

    4PDT to SPDT trick

    Yes, it does work now (with the 10k resistor), with only one small problem. The number 1 SPDT and the number 4 SPDT in the chip are connected to latching comparators that stay on once a mode is selected (by the switch), and indicate through an LED. To turn the comparator off when the mode is...
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