AC to DC voltage doubler not working

In summary, the voltage doubler will not double the voltage if there is any load. It will instead pump a DC current through the load. The voltage doubler involves a series capacitor. That is what limits your output current.
  • #1
electricalguy
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I have an AC to DC voltage doubler circuit. I am using a full wave bridge rectifier that uses two diodes and two capacitors that are 470uFarad each. My supply is a 50 watt transformer that outputs 13.9 volts and 3.790 amps. The supply frequency is 60 hz. The output frequency is 120 hz from the rectifier. The voltage output is 3.72 volts DC at 1.650 amps DC. I already know that the power supply is too low for the load I have which has a resistance of 2.3 ohms. My question is how do I calculate the power required to be able to allow the doubling effect to happen?
 
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  • #2
electricalguy said:
I have an AC to DC voltage doubler circuit. I am using a full wave bridge rectifier that uses two diodes and two capacitors that are 470uFarad each. My supply is a 50 watt transformer that outputs 13.9 volts and 3.790 amps. The supply frequency is 60 hz. The output frequency is 120 hz from the rectifier. The voltage output is 3.72 volts DC at 1.650 amps DC. I already know that the power supply is too low for the load I have which has a resistance of 2.3 ohms. My question is how do I calculate the power required to be able to allow the doubling effect to happen?
1) show us your schematic
2) show us a photo or 2 ( sharp and well lit) of your construction
 
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  • #3
I notice that 28 volts across 2.3 Ohms is 340W which is too much for the transformer.
 
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  • #4
tech99 said:
I notice that 28 volts across 2.3 Ohms is 340W which is too much for the transformer.

yeah, it's a wonder the resistor didn't vaporise in a puff of smoke
 
  • #5
It will not double the voltage if there is any load. It will instead pump a DC current through the load. The voltage doubler involves a series capacitor. That is what limits your output current.
You know that C = Q / V; and Q = I · t; So C = I · t / V; or I = C · dv / dt

One cycle of 60 Hz takes 16.667 ms, so half a cycle takes 8.33 msec = dt.
Secondary voltage 13.9 Vrms has a Vpp of 13.9 * 2 * Sqrt(2) = 39.3 Vpp = dv

C · dv / dt = Iout; 470 uF * 39.3 V / 8.333msec = 2.21 amps
That ignores voltage drops across diodes and in the secondary winding.
It also explains why your output current is limited.

There are several voltage doubler topologies possible. Please provide a circuit diagram.
Drag and drop a circuit .jpg or .png onto your next post.
 
  • #6
What happens if you test it with no load?
 
  • #7
The transformer output voltage is RMS, I suppose, therefore the 13.9 VRMS translated into 19.6 VPEAK. Allowing for 0.6 V drop across the diodes, the doubler would produce open circuit voltage of 38 V. At that voltage, the current across 2.3 Ohm resistor would 16.5A and the power would be 628 W. Way out of the transformer specs.
Why do you need a doubler?
What power do you need to deliver to the resistor?
 
  • #8
and yet another OP @electricalguy who hasn't returned to the thread :frown:Please check in and respond to questions and comments :smile:
 

1. Why is my AC to DC voltage doubler not working?

There could be several reasons why your AC to DC voltage doubler is not working. It could be due to a faulty component, incorrect wiring, or insufficient power supply. It is important to check all these factors to determine the cause of the issue.

2. How do I troubleshoot my AC to DC voltage doubler?

To troubleshoot your AC to DC voltage doubler, you can start by checking the power supply and ensuring that it is within the recommended range. Next, check the wiring and connections to make sure they are secure and correct. You can also test the components individually to identify any faulty ones.

3. Can a damaged component cause the AC to DC voltage doubler to not work?

Yes, a damaged component can definitely cause the AC to DC voltage doubler to not work. If any of the components, such as diodes or capacitors, are damaged or faulty, it can disrupt the flow of electricity and prevent the voltage doubler from functioning properly.

4. How do I know if my AC to DC voltage doubler is receiving enough power?

You can use a multimeter to measure the input voltage of your AC to DC voltage doubler. If the voltage is significantly lower than the recommended range, it could indicate that the power supply is not sufficient. You can also check the current rating of the power supply to ensure it meets the requirements of the voltage doubler.

5. Can incorrect wiring cause the AC to DC voltage doubler to not work?

Yes, incorrect wiring can definitely cause the AC to DC voltage doubler to not work. It is important to follow the wiring diagram provided by the manufacturer to ensure that all connections are made correctly. Incorrect wiring can lead to a short circuit or disrupt the flow of electricity, preventing the voltage doubler from working.

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