Motor acting weird

LesJones

Joined Jan 8, 2017
3,127
It is possible to exceed the maximum collector emitter voltage. It is an alternative way to destroy a transistor to exceeding the maximum base current that you have tried. (As would exceeding any of the maximum ratings.) The first table on semiconductor datasheets is normally the maximum ratings.

Les.
 

LesJones

Joined Jan 8, 2017
3,127
When the transistor is not conducting the answer is yes. (It will be equal to the battery voltage.) When the transistor is conducting there will probably be a small increase in the saturation voltage due to the motor taking more current with a higher voltage across it. If the load current did not change then the saturation voltage would not change.

Les.
 

Thread Starter

Man10

Joined Jul 31, 2018
55
When the transistor is not conducting the answer is yes. (It will be equal to the battery voltage.) When the transistor is conducting there will probably be a small increase in the saturation voltage due to the motor taking more current with a higher voltage across it. If the load current did not change then the saturation voltage would not change.

Les.
So if the load current does not change then the saturation voltage will not change?
 

Audioguru again

Joined Oct 21, 2019
2,976
Do you have a proper battery charger for a single Lithium-Ion cell? Have you tried charging the cell?
Did you measure the voltage across the motor when it tries to run and lift the arm?
Did you try a new TIP110 with a 330 ohm base resistor?
 

LesJones

Joined Jan 8, 2017
3,127
Re post #44. The simple answer is that it will not change due to a change of battery voltage. Temperature change probably will change the saturation voltage slightly. With a battery voltage of about 3.8 volts the saturation voltage of a Darlington transistor is significant. I don't think you choice of transistor is a very good one. A logic level mosfet such as a FDS8896 would have a saturation voltage of less than 0.1 volts. So when your battery voltage was 3.8 volts there would be 3.7 volts across the motor.

Les.
 

Thread Starter

Man10

Joined Jul 31, 2018
55
Re post #44. The simple answer is that it will not change due to a change of battery voltage. Temperature change probably will change the saturation voltage slightly. With a battery voltage of about 3.8 volts the saturation voltage of a Darlington transistor is significant. I don't think you choice of transistor is a very good one. A logic level mosfet such as a FDS8896 would have a saturation voltage of less than 0.1 volts. So when your battery voltage was 3.8 volts there would be 3.7 volts across the motor.

Les.
Collector emitter voltage and saturation voltage are not the same thing?
 

LesJones

Joined Jan 8, 2017
3,127
When the transistor is in saturation the saturation voltage is the same as the collector emitter voltage. The collector emitter voltage RATING is the MAXIMUM voltage that can be applied between collector and emitter when the transistor is NOT conducting. (From memory I think this is 60 volts for the TIP110)

Les.
 
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