5 Replies Latest reply on Oct 18, 2019 5:24 PM by dougw

    How to Reduce low AC voltage

    cricket-15

      not sure this is the correct place to ask this or not but here goes, i have a 3 amp 120 volt AC step-down transformer to 20 volt AC, i want to reduce the 20 volts to 10 volts AC, i tried splitting it with two 50 watt resistors but they get very hot without a load, how can i reduce the 20 volt AC to 10 volt AC?

       

      i've attached a picture of the transformer. any help i can get will be greatly appreciated.

        • Re: How to Reduce low AC voltage
          dougw

          There are several options - the first one is probably the least work:

          1. Obtain a transformer that converts 120 vac to 10 vac
          2. Use a second transformer to convert 20 vac to 10 vac
          3. Convert to DC and use an oscillator to generate 10 vac
          4. Install a series resistor equal to the load impedance, so half the voltage is across the resistor and half across the load
          5. Install a series resistor equal to the load impedance followed by back-to-back Zener diodes to clamp the output to 10 vac
          6. Run a 120 vac motor connected to a 10 vac generator
          7. Install back-to-back Zener diodes in series to reduce to voltage across the load (they will have to dissipate significant power and they distort the waveform)
          4 of 4 people found this helpful
            • Re: How to Reduce low AC voltage
              cricket-15

              here's what i'm trying to do, i want to use it for Etching and Marking of metals, I've converted the 20VAC to DC, the output DC volts are higher than the AC volts,  it works as i have it set up today but puts out too much voltage and the product gets hot and becomes hard to work with. Ideally i would like to be able to have variable output power but i am not able to get anything to work, i tried using an AC speed controllers, Rheostats and pods but they do not lower the 20 volts, i know enough about electronics to be dangerous ... and am looking for some help..

               

              current config

              1 of 1 people found this helpful
                • Re: How to Reduce low AC voltage
                  dougw

                  A variac (variable transformer) would allow you to adjust the voltage to whatever you wanted.

                  What is the load?

                  Is it heater in an etchant bath or some sort of motorized tool?

                  A simple adjustable DC-DC converter module would allow the output voltage to be adjusted without generating a lot of heat.

                • Re: How to Reduce low AC voltage
                  colporteur

                  What about half rectifying instead of full rectifying. Doesn't that impact output voltage? Old man using his old electronics knowedge.

                   

                  Sean

                  1 of 1 people found this helpful
                • Re: How to Reduce low AC voltage
                  beacon_dave

                  I think you bought the wrong train set...

                   

                  Lionel appear to do a hobby transformer with split variable outputs: 

                  CW-80 80-Watt Transformer