Help please

Status
Not open for further replies.
M

mark sheldon

New Member
Hi I have built the circuit below, I am using a 9v battery as the power supply, unfortunately when the motor is running the battery gets extremely hot, how could I prevent this from happening please? Any help will be extremely appreciated
 

Attachments

  • 13AD31D5-B385-445A-99AD-E5D0675B66D0.jpeg
    216 KB · Views: 174
If you mean the little 9v batteries used for radios and smoke alarms, there is your problem.

The battery is far too small, and will not last long when powering a motor.

Using several AA size batteries may be a better option.
How much current does the motor take?

JimB
 
mark sheldon said:
Hi I have built the circuit below, I am using a 9v battery as the power supply, unfortunately when the motor is running the battery gets extremely hot, how could I prevent this from happening please? Any help will be extremely appreciated
Click to expand...


You may have something wired incorrectly (a short or improper resistor value). But, as Jim said, the little 9V battery is not intended for large loads. Typically, loads under 100 mA should be used with 9V batteries.
 
With a 9 volt supply there is not a problem.
BUT "5-30v BATTERY/SUPPLY" It is possible to get more than 20 volts on the gate of the MOSFET with a 30V supply. Most all MOSFETs should not see more than 20V Gate-Source.
 
You need a reverse-biased power diode across the motor to protect the FET from the voltage spike which occurs when the FET switches off.
 
Battery ESR must be much lower than motor DCR and FET RdsOn

A better way is divide down a stable Vref to 50mV with LM358 or sense to ground OpAmp then sense current with max expected surge 10x? And choose R sense.

Then torque control is 0 to 50mV

Avalanche diode protected FET is needed.
 
Status
Not open for further replies.

Similar threads

T
  • Question
please help
Replies
6
Views
1K
timmychangga
T
F
  • Question
Help with Serta remote circuitry please
Replies
3
Views
1K
ZipZapOuch
T
  • Question
Combinational logic please help
Replies
3
Views
2K
timmychangga
T
T
  • Solved
please help, i need this circuit to work :(
Replies
13
Views
2K
shokjok
S
J
PLEASE HELP!
Replies
16
Views
2K
Tony Stewart
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…