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  1. hevans1944

    Find a substitude mosfet

    Why not order this part and replace the two ruined MOSFETs? It appears to still be in production with lots of vendors. See here. How did you manage to ruin two MOSFETs? If you don't know what you are doing, why are you doing it? Letting the smoke out of components is a time-honored way of...
  2. hevans1944

    Pic interface with sensor

    Whew! It is nice to know that you DO have some help. This would be quite a project for a production team of, say, six or seven experienced members, to include marketing and sales people who would decide how to place the end product for maximum return on investment. School is different. Most...
  3. hevans1944

    lighting a 7 segment LED

    @Mark2019: No, first is learning how to read and observing this thread was started on November 11, 2013. @KrisBlueNZ sadly passed away in 2015. We miss him, but this thread is DEAD. It should have been closed by a moderator after November 27, 2013 when @ligo.george made the last relevant post...
  4. hevans1944

    Pic interface with sensor

    Why would you choose a project requiring design skills that you haven't developed yet? There are plenty of off-the-shelf commercial gas sensors available. How are you advancing the state of the art by trying to re-invent this particular wheel? Does someone hand out Post Graduate Certificates...
  5. hevans1944

    Pic interface with sensor

    @Rajinder: With almost no effort, I found this DC-to-DC buck converter with a wide range of adjustable output voltages. You might want to pick up a couple to "play" with. DigiKey will sell you two for about $17.00. Here is a link to a page where you can view or download the datasheet for the...
  6. hevans1944

    Pic interface with sensor

    I do like the idea of an adjustable, low-voltage-regulated supply, with its output to the heater somehow controlled by an FET (MOSFET, really) without losing the voltage regulation. There should be a way to do this; you just need to find it. Meanwhile, I will try my luck with Google to see what...
  7. hevans1944

    Pic interface with sensor

    A schematic would be good. Are you "hoping" to somehow take the 0.65 V DC pulse from the drain of the FET? Is the drain connected, through an unspecified resistor, to the positive DC output of an adjustable voltage regulator, nominally set to produce 0.65 V DC? If so, there will be zero output...
  8. hevans1944

    What is wrong with my wireless circuit?

    He listed the encoder and decoder modules but did not specify the 433 MHz RF transmitter and RF receiver modules. The receiver module is shown with two DATA outputs, and both of these are connected to pin 14 of the HT12D decoder. Connecting outputs together generally does not work. It might be...
  9. hevans1944

    How would a twisted pair effect a signal

    ...Which is not a bloody likely scenario in automotive applications, where all signals are referenced to the almighty chassis ground. Still, where it IS effective, twisted-pair is an economical solution to common-mode noise. As @Audioguru points out, Western Electric and AT&T have been using it...
  10. hevans1944

    How would a twisted pair effect a signal

    I have been using farkle for many years to mean any activity based on obtaining random results through experimentation, without any underlying basis of understanding of what is cause and what is effect. Fun way to pass idle time, I suppose. IIRC, I first heard it used in 1960s, way before I...
  11. hevans1944

    How would a twisted pair effect a signal

    I doubt whether the twisted pair of 16 ga. wires has any causal effect on what you are seeing. Poor connection continuity, temporarily remedied by disconnecting and re-connecting the affected connector or connectors, is a more likely cause. Why not test this theory by removing the twisted pair...
  12. hevans1944

    Pic interface with sensor

    Your reply raises more questions than it answers, and it answers NONE of the questions I have asked. Based on the lack of any informed response from you, I don't see how anyone here has provided you with any help. You say you are trying to design a gas alarm as part of your PGC project. What is...
  13. hevans1944

    Pic interface with sensor

    Waiting doesn't get anything accomplished. You have to be proactive. Did you read the Electronics magazine article that @Bluejets linked to? Did you try to find and read any of the references cited at the end of the article? Have you defined your range and resolution measurement requirements...
  14. hevans1944

    Pic interface with sensor

    It is your JOB to learn as much as possible about this sensor, and your intended application of it, before proceeding any further with this thread. Anything else is a total waste of our time because you will either be unable to ask intelligent questions about it or you will ask questions whose...
  15. hevans1944

    Pic interface with sensor

    Neither do I, and obviously @Rajinder doesn't either. So, the first thing I would do is beg, borrow, or <gasp> buy one to try it out on a breadboard setup. It is especially important to get the pulsed application of VH and VC performed properly. The datasheet offers a pretty good starting point...
  16. hevans1944

    Isolation Transformer?

    WTF would anyone with an engineering degree choose to use highly inefficient Peltier thermoelectric heat pumps for anything other than spot-cooling hard-to-access components? AFAIK no one uses TECs to cool an entire server rack, much less a data center full of server racks. And how are you...
  17. hevans1944

    Frustration over IR transmitter and receiver how do I..?

    The OP was "experimenting" with a receiver designed to demodulate a 38 kHz PWM pulse train, which is the type of signal typically produced by common hand-held IR remote controls. Why modulate at 38 kHz? Because the ambient environment is full of infrared radiation that would interfere with an...
  18. hevans1944

    Explain why DMM reads 00.0 on negative side of circuit

    Those videos are better than nothing. I didn't spot any errors in the presentation, but the explanations seemed too long and too complicated. However, if it helps you to understand electricity, the videos will have served their purpose. I would keep looking though. I am sure there are better...
  19. hevans1944

    Explain why DMM reads 00.0 on negative side of circuit

    Ooops. So it is.
  20. hevans1944

    Explain why DMM reads 00.0 on negative side of circuit

    @stspringer perhaps my response was a little too harsh, but from my point of view we have been working with you for weeks without seeing any progress in your understanding of electricity. I hope that EP is not your only resource for the study of electricity, because this is not a teaching forum...
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