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1. 

   gbulmer
   Moderator

   I'd use the TC4428. It seems tidier, and more symmetric.

   There should be nearer the same propagation delay to the two outputs on the MOSFETs going through the TC4428.

   To be honest, that chip is so fast that it shouldn't matter much, but the capacitance into the output MOSFET gates might slow one side w.r.t. the other.

   Also, the output drive of the TC4426 is a much higher voltage than logic-levels, and I'd rather not subject an input to that level.

   Finally, once you are happy with it all, you might remove the optoisolator, at which stage I'd prefer not to have a higher-voltage output connected to an input side, just in case I made a mistake wiring or a short happened.

   But I am very conservative.

   Posted 4 years ago #
2. 

   Silntknight
   Moderator

   Also, the output drive of the TC4426 is a much higher voltage than logic-levels, and I'd rather not subject an input to that level.

   I am running an input signal at 12V... The datasheet says that it maxes at +22.3V, so I am still well within safe margins, but there should be no problem with connecting the output to the input. Either way, I agree with using the TC4428. Also, I didn't really realize that I could run the TC442* off of the 3.3V the Maple provides, so I will make another test circuit to try that. If the input signal doesn't need to be the same as the output voltage and it runs fine on 3.3V, then I'd rather run it off 3.3V because my board would be much simpler as a result.

   About removing the opto, I was asking about that earlier. I think I will keep it as extra protection (this is going to be in an electrically noisy area). Also, I'd rather keep the high voltage (12V) circuits completely independent from the low voltage (3.3V and 5V) circuits.

   Also, anyone have an theoretical equations for the force provided from a solenoid based on the number of coils? I could pull out my AP physics equation sheet, but we don't cover inductors, so I don't know if I have that equation. Still, if I know the force provided, I can figure out how quickly the inductor should move in a frictionless vacuum.

   Posted 4 years ago #
3. 

   gbulmer
   Moderator

   I imagine you've found this solenoid force calculator:
   http://www.daycounter.com/Calculators/Magnets/Solenoid-Force-Calculator.phtml

   Posted 4 years ago #
4. 

   Silntknight
   Moderator

   Yeah, I actually did. Thanks! Unfortunately, I doubt its accuracy because I made a 100 turn solenoid with a 1mm gap and I ran it at 6V. The coil's resistance was .6 ohms so there was a significant amount of current, yet no core movement. So I might just have to buy one.

   Posted 4 years ago #
5. 

   gbulmer
   Moderator

   Silntknight -
   I imagine the diameter of wire of 100 turns of something which had 0.6 ohm resistance is small.
   what diameter of wire was that? About 30 AWG (0.025mm)?
   Was it a solid iron core, or was it a hollow tube. That would change the cross sectional area of the coil a lot.

   Certainly to get a handle on what might work, buy a solenoid.
   There are usually solenoids in old scrap cars (though the copper is valuable), which might be very cheap.

   Posted 4 years ago #

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