Constructing a 1Hz 50 Hz 500 Hz 5Khz 30 Khz 50 khz Switching Device

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Discussion Overview

The discussion revolves around the construction of a switching device to pulse DC voltage from 9-12 volt batteries at various frequencies (1 Hz, 50 Hz, 500 Hz, 5 kHz, 30 kHz, and 50 kHz). Participants explore methods for pulsing the voltage to a supercapacitor while considering protective devices to prevent overcharging.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants suggest that pulsing the voltage from 0 volts to 12 volts should prevent overcharging a 12V rated capacitor, recommending a safer peak voltage of 10 volts.
  • Others propose using a 555 timer chip as a simple method to generate the desired frequencies.
  • There are discussions on using MOSFETs to switch current to the capacitor, with some noting that the voltage across the capacitor may not appear as a pulse but rather as a rising voltage.
  • One participant expresses concern about the possibility of overcharging the capacitor when pulsing with DC voltage through a diode, questioning the safety of the approach.
  • Another participant clarifies that a diode will only conduct if the voltage exceeds the capacitor's current charge, suggesting that this mechanism prevents overcharging.

Areas of Agreement / Disagreement

Participants express differing views on the safety of charging a capacitor through pulsing DC voltage and the implications of using diodes in the circuit. The discussion remains unresolved regarding the best methods and components to use for protection against overcharging.

Contextual Notes

Participants have not fully clarified their assumptions regarding the behavior of capacitors in pulsed circuits, and there are unresolved questions about the specific configurations and components needed for the proposed device.

gedfire
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Hello All,

I am thinking about pulsing the power from individual 9-12 volt Batteries @ the different frequencies of 1 Hz, 50 hz, 500hz 5 khz 30 khz and 50khz .


All I want to do is to create a pulse DC charge from a 9 volt or 12 volt battery.Car or Motor Cycle batteries are my targets.

I want to pulse this DC voltage using as little amperage as possible to a capacitor.Now I would also want to know what kind of protective device I could use to prevent the Super Capacitor (50F at 12 volts ) from over charging? Zener Diode, varistor,gas discharge tube etc? Please let me know the best components to use and if possible, the specifications based on the parameters I have outlined.

Can MOSFETS be used? If so how? The simplified version if possible please:biggrin:



Gary
 
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If you produce pulses that vary from 0 volts to 12 volts, then you can't overcharge your 12 V rated capacitor. Make it 10 volts to be safe.

You can generate a range of frequencies in many ways, but an easy way is to use a 555 chip. You can find a circuit that uses only one resistor and one capacitor if you use Google in image mode.

A MOSFET can be used to switch the current to the capacitor, but the voltage across the capacitor will not look like a pulse. It will be like a charging capacitor where the voltage is rising to the peak value of the input pulse.

You can limit the current by placing a suitable resistor in series with the capacitor.

Perhaps you could explain what you are trying to do?
 
gedfire said:
Hello All,

I am thinking about pulsing the power from individual 9-12 volt Batteries @ the different frequencies of 1 Hz, 50 hz, 500hz 5 khz 30 khz and 50khz .


All I want to do is to create a pulse DC charge from a 9 volt or 12 volt battery.Car or Motor Cycle batteries are my targets.

I want to pulse this DC voltage using as little amperage as possible to a capacitor.Now I would also want to know what kind of protective device I could use to prevent the Super Capacitor (50F at 12 volts ) from over charging? Zener Diode, varistor,gas discharge tube etc? Please let me know the best components to use and if possible, the specifications based on the parameters I have outlined.

Can MOSFETS be used? If so how? The simplified version if possible please:biggrin:



Gary

You other similar thread and this one are very confused and confusing. Could you please say exactly what you are trying to do?
 
vk6kro said:
If you produce pulses that vary from 0 volts to 12 volts, then you can't overcharge your 12 V rated capacitor. Make it 10 volts to be safe.

You can generate a range of frequencies in many ways, but an easy way is to use a 555 chip. You can find a circuit that uses only one resistor and one capacitor if you use Google in image mode.

A MOSFET can be used to switch the current to the capacitor, but the voltage across the capacitor will not look like a pulse. It will be like a charging capacitor where the voltage is rising to the peak value of the input pulse.

You can limit the current by placing a suitable resistor in series with the capacitor.

Perhaps you could explain what you are trying to do?

Hi,

Thank you for replying.You say I cannot overcharge a capacitor as long as I pulse it with a suitable voltage.I am pulsing it with a dc voltage through a diode.I thought the charge would accumulate until it passes the voltage rating and possibly explode?

I am trying to pulse charge a capacitor though a diode placed on one leg.

If you need anymore details please let me know.

Ged
 
berkeman said:
You other similar thread and this one are very confused and confusing. Could you please say exactly what you are trying to do?

Thanks for stating your position.

I am trying to charge a capacitor through using a diode on one leg.Like this:



but with a solid state version like this:



In this video the capacitor voltage increased...what if the gentleman had allowed the charging to continue?
Hope this answers your questions.After charging the capacitor,I want to use it to power a load safely.

Thanks

Ged
 
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gedfire said:
Hi,

Thank you for replying.You say I cannot overcharge a capacitor as long as I pulse it with a suitable voltage.I am pulsing it with a dc voltage through a diode.I thought the charge would accumulate until it passes the voltage rating and possibly explode?

I am trying to pulse charge a capacitor though a diode placed on one leg.

If you need anymore details please let me know.

Ged

No, that can't happen.

The diode will only conduct if the voltage on its anode is more positive (by at least 0.7 volts) than the voltage on the cathode.

So, if the capacitor is already charged to, say, 11.3 volts, the voltage on the anode has to be at least 12 volts before the diode will conduct.

If the peak input pulse value is 12 volts, then charging will stop.
 

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