New lower price for Axon II ($78) and Axon Mote ($58).
0 Members and 1 Guest are viewing this topic.
and I am sure the pins are connected correctly.
The 9V batteries put out 2.8A with a negligible load
The transistors start heating up as soon as I plug in the batter leads, not when I turn the motor on.
I will venture to buy and program a PIC to do some PWM for speed control of these motors but I think there must be something wrong with the way I have this setup.
Should the transistors be getting extremely hot?
My goal is to construct this remote controlled device from scratch and simple pieces. Id like to avoid purchasing parts to do most of the tasks for me (i.e. speed controller) so I can learn to do it myself.
put a small resistor on the base/gate of them, otherwise the base-emitter current will be very high and it might even damage the transistor.
another thing to remember. some transistors need to have a bit higher potential on the base than in the collector, to fully open. otherwise, if base=collector, they will open at about (collector/base+0.7 * 100 %), which means high inefficiencies at low voltages. if the collector-emitter resistance is high, this inefficiency will translate directly into heat dissipated by the internal R, and hopefully by a heatsink.
Soeren, to what are you referring, i wrote E and C several times there it depends on the transistor type (PNP/NPN or chan N/P, though)
Soeren, a new 9V energizer batter puts out about 2.8A when connected to a multimeter. I considered this negligible.
oh, i wasn't referring to the base-collector circuit at that point.the idea is that the transistor has a voltage on the collector, and (a BJT at least), should have at least +0.7V more on his base than on his collector to fully open. so, base = collector + 0.7
edit: hmm, something sounds wrong here. don't regard this post, contains amateur's opinion