Short-Circuit Protection using transistors

Thread Starter

Rod Zero

Joined Nov 6, 2014
9
Hi there!

I'm designing a short-circuit protection circuit for x2 AA Battery(3V) and I'd like some tips from the community on how can I make it a better designed and low power mode circuit. When V_out is short cirtcuited, the buzzer is activated. The problem is that the power consumption, when there's no load, is located at the 10k resistor. I'd like some tips on how can I make it a better designed circuit. Do you think a optocoupler ic is a good idea? Any tips how can I implement it on this design?

short_circuit_transistor_aa.png
 

crutschow

Joined Mar 14, 2008
25,632
I don't think that circuit does what you want. It looks like latch.
Where did you get that circuit?

What short-circuit current are you trying to limit (from where to where)?
 

Thread Starter

Rod Zero

Joined Nov 6, 2014
9
I don't think that circuit does what you want. It looks like latch.
Where did you get that circuit?
- https://circuitdigest.com/electronic-circuits/short-circuit-protection-circuit-diagram

What short-circuit current are you trying to limit (from where to where)?
When the ‘short’ occurs the output voltage drops to 0V and Transistor #01 stops conducting Now the current is started flowing through the buzzer and pass through the ground via the short circuit path indicating that a short has been detected. And the current is diverted through the Buzzer instead of damaging the entire circuit.
 

crutschow

Joined Mar 14, 2008
25,632
To reduce standby current remove R3, replace Q1 with an N-MOSFET, Q2 with a P-MOSFET, and add a 1meg resistor between the gate and source of Q2.
Both MOSFETs must be logic level types (Vgs(th)≤2V).
 

MisterBill2

Joined Jan 23, 2018
7,234
You could just have a low resistance buzzer in series with the load, and when the load was not drawing excess current the buzzer will be silent, but when the current exceeds a limit the buzzer will buzz, both limiting the current and sounding the alarm.
What we need to know is how much current is acceptable, and what voltage must be available at Vout when there is no short circuit.
Really, a description of what this circuit is part of may get you an answer that is better yet.
 
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