Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Recent content by Gary_SMi

  1. G

    Mosfet IRF9530 Circuit Issues

    Makes sense Klaus. The power supplies are standard in the field for the relay operated systems so not practical either. There are 3 different ways they are used. 1.) All 10 start same time (most demanding) 2.) 5 start at a time. 3.) Software controlled where they start stop different times -...
  2. G

    Mosfet IRF9530 Circuit Issues

    Thanks Klaus, the whole thing starting to make sense now. Replaced with the 74A fet, performs way better. The power supply on startup of all 10 at the same time virtually hits 4v before recovering, when all running its ok at 12v or so. In the system all 10 are switched at the same time from time...
  3. G

    Mosfet IRF9530 Circuit Issues

    Hi, On scope notice minor differences with addition of the schottkys and capacitors etc. Even the ones with the diodes and capacitors are failing in the field. To increase the dv/dt would the introduction of a capacitor on the gate do the job? Have also just got some IRF 4905 fets rated 74A...
  4. G

    Mosfet IRF9530 Circuit Issues

    Thanks Klaus, will try the above. In the field wiring from supply is short but wiring to the motors can be up to 30M ... 2.5mm cabtyre. Also there are instances where more that 1 motor is energised at a time even some cases all 10 motors are energised simultaneously....
  5. G

    Mosfet IRF9530 Circuit Issues

    Hi Klaus, Thanks for your reply. Attached pics, the power supply is 29A 12VDC Meanwell unit. Is it possible the addition of the schottkys would have solved the problem? It seems I cannot get the unit to fail on the test bench, but in the field they are failing..... - - - Updated - - -...
  6. G

    Mosfet IRF9530 Circuit Issues

    Hello, Attached describing part of a 10 channel mosfet motor drive circuit. It seems that channels are failing from time to time, either the bjt or the fets are failing either permanently ON or permanently OFF. Have recently added the schottky diodes in an attempt to rectify the problem. Can...
  7. G

    P-Channel Mosfet Application

    Hello Vbase, am needing to add some functionality to your circuit as outlined in the attached pic. The problem I am having is that the fet banks are triggered when bank enable goes high even when card enable is low? Do you have any suggestions on a better way to accomplish this?
  8. G

    P-Channel Mosfet Application

    Thanks Vbase made board using transistor method as outlined in your drawing and works 100%. Initially went the OC route to provide isolation to/from the PLC network but if unnecessary, this works perfectly and more efficient & economical, with Uc and 24Vac inputs either/or/both. Much appreciated :)
  9. G

    P-Channel Mosfet Application

    The load is 3A inductive dc motors (fets still get hot with the pic input but not the 24vac inputs, have reworked resistor values and removed led's etc, Flywheel diode across load also makes no difference. The fets are MTP2955E, 8A. Will try circuit from Vbase recommendation.
  10. G

    P-Channel Mosfet Application

    Thanks Vbase, this looks like a much more efficient way of doing things will give it a try in the week :)
  11. G

    P-Channel Mosfet Application

    Hello Vbase, it would be appreciated if you could send a drawing of a better way to do this fets still getting hot, many thanks
  12. G

    P-Channel Mosfet Application

    Thanks, yes the bridges are on the reverse side. Also, haven't indicated there is a LED on the output of the OC in line with the 10K resistor. The gate of the FET is directly to the OC. Seems there is a damaged FET from my attempts, would you consider the OC output and drive circuit to be ok? -...
  13. G

    P-Channel Mosfet Application

    Thanks for that, will make the changes. At the moment the 5V section is not being energised at all. Have placed bridge and opto circuit for the first 2 channels but when I apply the 24V ac to either of the channels it seems to switch both OC' s on, any suggestions? As well as the fact that...
  14. G

    P-Channel Mosfet Application

    Hi FvM, Yes P channel, connected as attached? Will rework the isolation as per your suggestion and retest. As for the 5V trigger illustrated by S1 and the diodes, maybe it will be better to place this then on the OC output side with transistors rather?
  15. G

    P-Channel Mosfet Application

    Hello, I have 5 x 8A mosfets that need to drive individual loads. They need to be triggered in 2 ways, 1.) all 5 triggered together from 1 microcontroller output or 2.) They need to be triggered individually from 24Vac plc outputs. Have tried as attached but produces undesirable results and the...
See more

Part and Inventory Search

Back
Top