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Dual Voltage DC Motor

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me_guitarist

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Dear guys!!! On a 12V DC miniature motor,can I add a zener diode in series on +VE (or maybe -VE) to run at 24V DC without affect its current? Any suggestion?
 

If Zener diode is rated for higher current than the motor - you can ..
If not, you can implement Zener follower .. see picture below ..
In both cases you have to be aware of possible heat generation ..

Regards,
IanP
 

Dear IanP,
The DC motor will generate around 50mA@12V DC,
what's the zener diode,resistor & transistor value should I use according to yr ideals?
 

For 12V output you need 13V zener diode (500mW), as R you can use 1kΩ and transistor can be of almost any type (Ic>500mA), something like 2N2222 (N100, BC337, BC639, BD135, ..) will do ..
Rc<100Ω (0.5W) or not used at all ..

Regards,
IanP
 

ok,I got BC546B transistor, should be no problems?
Assuming 24V go into Vin, GND means -VE rite? Vout = 12V?

Thanks!
 

BC546 is rated only for Ic< 100mA but in motor applications you should really look for something rated for higher current ..

Assuming 24V go into Vin, GND means -VE rite? Vout = 12V?
Click to expand...
Correct ..

Regards,
IanP
 

ok, I'll look for higher current transistor

Added after 1 hours 28 minutes:

or can I exclude the transistor?
 

If your motor doesn't draw more than 50mA you can try to use only 12V zener diode, but make sure that it is rated for at least 1W ..

Regards,
IanP
 

Can I wire like this with 1w12V zener diode?
63_1164004208.jpg
 

You need to use the zener voltage (12V) and not the forward voltage (0.7V) ..
Connect the 12V zener diode the opposite way around (cathode to 24V) and it should work ..

Regards,
IanP
 

Like This?
93_1164115173.JPG


Added after 38 minutes:

Whats the defference between the above & this wiring?
7_1164117459.JPG
 

dod you know at the start of power supply motor take nearly 800ma - 1a.?
 

my motor won't take tat high current,beow 100mA on starting...
 

use 2 X 6volts zeners

500 mw zeners is all thats needed at 12 volts

or ~ this value for a 1 amp standing current


maybe also add a 12v clamp zener on the + rail
 

2 x 6V zemers in series or parallel?my motor only need 50mA@24V DC
 

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