Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: MasterRyko on July 11, 2007, 09:25:10 AM
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We are getting way too much heat from our transistor in our motor driver circuit. We can't use a lower resistor because of current restrictions. Are there any alternatives? We need 1 amp to run our motor and we're using a TIP31 NPN transistor with a 340 ohm resistor and a 5 volt source.
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The heating is normal and inevitable. You must attach some metal(aluminium) plate to the back of your transistors(use those holes that big transistors usually have, they are supposed to be holes for screws) and/or install a mini brushless fan. I like fans, personally.
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how much is the base current? it should be in the mA range but you could check anyways.
Also as Tsukubadaisei said, attach a heatsink and if heat is still too high (getting too close to 150°C for TIP31) then you must use a fan.
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For motor control you should use a MOSFET (http://www.societyofrobots.com/electronics_advanced_components_tutorial.shtml#mosfet) with a big 'ol heatsink on it, not a transistor.
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Well I would go with a H-Bridge, if its for motors, lots more features and simpler to work with than building your own H circuit out of MOSFETS
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For motor control you should use a MOSFET (http://www.societyofrobots.com/electronics_advanced_components_tutorial.shtml#mosfet) with a big 'ol heatsink on it, not a transistor.
I agree that MOS-FET are easier to control than PN-junction transistor but there are printers that use PN transistors in their motor drivers. I dont know why but I think it depends on the case.
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a mosfet is still a transistor.
For digital circuits it has many advantages, but if you compare:
a bjt transistor can achieve saturation with less voltage (though 5v is enough for many mosfets and even 3.3, 2v or less might be a problem)
If space is a concern, a bjt transistor can drive more current in less space.
But of course, they can handle higher temperatures, have less current consumption and are easier to implement as on-off switches.
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a mosfet is still a transistor.
exactly. just to make things clear:
Metal Oxide Semiconductor (electrical)Field Effect TRANSISTOR