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Topic: E-Chopper (ex. Expectations & Torque) (Read 8940 times) previous topic - next topic

dc42

It sounds a nice project!


Here is the circuit as used in the demo (previous)


The 220R/2k2 resistors form a voltage divider that reduces the gate drive voltage by 9% and hence increases Rds(on). I would ditch the 2k2 resistors and use instead a single resistor of 2k2 or 10K from the Arduino output pin to ground.

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I replaced those Z14's with some STP40NF10L's.


That's one of my favourite mosfets, however the Rds(on) is a little high for the current you are switching. I would go for something with Rds(on) less than 10 milliohms, maybe http://www.newark.com/jsp/search/productdetail.jsp?sku=70R7958.

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Each button goes to hardware debouncing (4093s) and then to respective input pins.  The debounced outputs also get diode-OR'd into the hardware interrupt pin.


Way over-complicated IMO, it's very easy to poll the buttons and debounce them in software - but if it works, no reason not to keep it.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

runaway_pancake


It sounds a nice project!

The 220R/2k2 resistors form a voltage divider that reduces the gate drive voltage by 9% and hence increases Rds(on). I would ditch the 2k2 resistors and use instead a single resistor of 2k2 or 10K from the Arduino output pin to ground.


Thanks, dc42!
When I re-built the FET circuit, I replaced the 2K with 20K? (I have a long strip of those.)  As a matter of fact, I got those STP's based on a recommendation of yours to another member.  I think I need to keep the 220?, in case the FETs crater again (nasty business that).  I might give the wholly unassisted acceleration from a dead-stop test another go, but right now I'm having fun.
"Who is like unto the beast? who is able to make war with him?"
When all else fails, check your wiring!

dc42


I think I need to keep the 220?, in case the FETs crater again (nasty business that).  I might give the wholly unassisted acceleration from a dead-stop test another go, but right now I'm having fun.


Yes, you need to keep the 220 ohm resistors. What I was suggesting was to move the 2K2 resistors to the other end of them - and then use just one resistor to ground since there is no point in having 2 in parallel.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

runaway_pancake


Yes, you need to keep the 220 ohm resistors. What I was suggesting was to move the 2K2 resistors to the other end of them - and then use just one resistor to ground since there is no point in having 2 in parallel.

O-I-C...  that way, there wouldn't be a divider. 
OK.
"Who is like unto the beast? who is able to make war with him?"
When all else fails, check your wiring!

runaway_pancake

I rigged up a battery tray using a baking pan.  It's pretty flimsy and flexes (too much) despite my "reinforcements".  But it's more casual than having the batteries around my neck, riding is more enjoyable this way.  I went about for around 4 miles and kind of went all free-style like in an empty parking lot this morning.

"Who is like unto the beast? who is able to make war with him?"
When all else fails, check your wiring!

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