I made a circuit based on the schematic below:
Diode using 1n5819 and R1 is VR.
This is the circuit I made:
I've try many trim pot and the circuit works at the beginning.
After seconds the voltage goes very high and I thought the IC has burned.
So I changed the new one and the same thing happened until I found a pot like the picture above and put it on the circuit.
When the circuit on, the pot gets very hot just after seconds.
This circuit has burned my two trim pot and I've checked all the wiring and found nothing error.
What's the problem with this circuit?
Diode using 1n5819 and R1 is VR.
This is the circuit I made:
An externally hosted image should be here but it was not working when we last tested it.
I've try many trim pot and the circuit works at the beginning.
After seconds the voltage goes very high and I thought the IC has burned.
So I changed the new one and the same thing happened until I found a pot like the picture above and put it on the circuit.
When the circuit on, the pot gets very hot just after seconds.
This circuit has burned my two trim pot and I've checked all the wiring and found nothing error.
What's the problem with this circuit?
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The resistor just get very hot and the voltage is unstable.
I think it's cause by the high temperature.
I think it's cause by the high temperature.
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R2 is 1K (two 2k in parallel) and the voltage is normally adjustable by the VR.
The problem is the unstable resistance of VR after the circuit has on.
The problem is the unstable resistance of VR after the circuit has on.
With such a layout built on a breadboard all kinds of troubles like unstable regulation can show up. Also, 5819 is not sufficient as in this case that with a less than optimum layout you risk blowing it due to high Backvoltage.
If necessar to use breadboard, try to make all tracks involving high currents at high speed as short as possible. It might help.
If necessar to use breadboard, try to make all tracks involving high currents at high speed as short as possible. It might help.
the high frequency section (chip, inductor, diode input terminal) is very close and i thought it's good enough.
Buy a new kit for only 2 USD might help 🙂
Buy a new kit for only 2 USD might help 🙂
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