Capacitor Dump Circuit - Negative Switching

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SUMMARY

The discussion focuses on a capacitor dump circuit utilizing an SCR, a 5.1V zener diode, and two 3.2V LEDs to charge a 36V battery from a 75V, 17,000 uF capacitor. The circuit operates by charging the capacitor to approximately 48V - 50V before dumping the charge. However, issues arise with the SCR latching, prompting suggestions to replace it with a FET for improved functionality. The circuit's design lacks regulation, which raises concerns about safety and operational effectiveness.

PREREQUISITES
  • Understanding of SCR operation and characteristics
  • Familiarity with FETs and their applications in switching circuits
  • Knowledge of capacitor charging and discharging principles
  • Basic circuit design concepts, including voltage regulation
NEXT STEPS
  • Research FET-based switching circuits for capacitor discharge applications
  • Learn about safe charging practices for battery systems
  • Explore voltage regulation techniques in power supply design
  • Investigate SCR alternatives and their advantages in similar circuits
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Electronics engineers, hobbyists designing capacitor discharge circuits, and anyone involved in battery charging systems seeking to enhance circuit safety and efficiency.

TxAggie00
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Hello All!

I have a question about negative switching for a capacitor dump circuit. Currently we are dumping a capacitor to 3 12VDC battery on the negative leg. We are using an SCR, 5.1V zener and two 3.2V LEDS. The capacitor is a 75V, 17,000 uF computer grade cap. The capacitor charges up to the battery voltage + the zener + the 2 LEDS (~48V - 50V) then dumps. We have some problems with the SCR "latching" and was told there was a better way using a FET. The problem is I am somewhat clueless on how that can be done. Anyone have any ideas?

Thanks,
Scott

Note: ignore the 33V zener in the attached picture. It is a 5.1V zener
 

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An SCR is supposed to latch. I'm not sure what this circuit is supposed to be. The left hand side looks like a simple power supply with simple filtering but no regulation. Then the battery is hooked across the output with an SCR. Looks to me like as long as the power supply output voltage is less than 48 volts or so nothing will happen. But as soon as it approaches 48 volts the SCR goes into conduction and latches on (how it is supposed to) and a 36 volt battery is being charged with a 48 volt source. Kinda scary. So what is it you are trying to do?
 

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