Help with DC Motor Back-EMF w/o Diode?

djsfantasi

Joined Apr 11, 2010
9,151
I am quite aware of a transistor being able to function as a diode, BUT for this application, a diode with adequate ratings should be simpler and probably less expensive, and certainly easier to get the correct connections than using a transistor. Diode voltage and current specs are simpler to understand, and that may be a benefit to those who are not extensively experienced in the field..
I totally agree that a diode may be the best choice.

BUT, the TS specified that he is limited in the components he has available. AND he has stated specifically that he does not have a diode. HENCE, using a transistor as a diode is his best choice.
 

shortbus

Joined Sep 30, 2009
10,044
BUT for this application, a diode with adequate ratings should be simpler and probably less expensive, and certainly easier to get the correct connections than using a transistor.
At it again are you? Read what the TS and everyone else has said, this is a school project, the TS ONLY has and is allowed to use what came in a package. AND THERE IS NO DIODE, NONE, NADA.
 

Tonyr1084

Joined Sep 24, 2015
7,776
@WhenYouNeedHelp NOT @MisterBill2
A PN junction is a diode. Within a transistor you have at least one PN junction. NPN has a PN in it. PNP has a PN in it. In the case using an NPN transistor as a diode you use the base as the Anode and the emitter as the Cathode. If using a PNP transistor then the emitter is the Anode and the base is the Cathode. You can ignore the collector in either case. Just think of current flow and the arrow acting like the diode directing the current.
Mr. Bill: Was answering the TS question.
Almost every solution I come across makes use of a diode but unfortunately, they were not provided with our course kit.
Transistor? Provided. Diode? Not provided. Reading and understanding the post? Priceless.
 
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