Introduction: DIY Tiny High Voltage Power Supply
Some projects require a high voltage power supply, like driving CFLs, neon bulbs, neon lamps, etc. These require a high voltage but there are very few high voltage power supplies that are compact and can power CFLs, CCFLs, and neon bulbs. So, in this Instructable, I will show you how to make a tiny High Voltage power supply that can be used to turn on CCFLs, CFLs, and neon bulbs and test them.
This project involves high voltages, please follow the necessary safety measures.
A ferrite core transformer
NPN BJT (I used a BD243C)
Step 1: Winding the Transformer
You need thin copper wire to wind the transformer. I used a premade transformer with around 100:1 Turns Ratio. It is very important that the transformer used has a feedback coil, or the circuit will not work.
To wind the Transformer, follow these steps:
1) Wind the secondary coil with around 300-500 turns. Wind a single layer then insulate the layer with electrical tape then wind again till you have made the required number of turns.
2) Put a few layers of insulation tape then wind the primary coil. Make the primary coil using multiple strands of thinner copper wire since it will heat less due to the skin conductor effect. Wind 3-5 turns of the primary coil. Insulate the winding then proceed to the next step.
3) To make the feedback coil, wind 10-15 turns of copper wire. Insulate the coil then glue the transformer core. The transformer is now complete.
Step 2: Solder the Circuit
Solder the circuit to a piece of perf board, try to keep the components as close as possible. The circuit diagram is given in the pictures. Refer to the diagram to solder the components. I have attached a few pictures of the finished circuit for reference. A screw terminal is used for the output since it makes the connection easy. The circuit is very simple and can be assembled in under 10 minutes.
Step 3: Testing and Troubleshooting
You can power on the circuit now. The circuit should work now. Try attaching a neon bulb or CCFL lamp to the output and check if it works. If it does not work, try the following:
1)Check if the circuit is correctly soldered.
2)Try using a higher voltage and an unregulated power supply. If you are using an SMPS, it may be going in overcurrent protection. Try using a battery.
3)Try reversing the feedback coil wires. This is a very common problem.
4)Try using a multimeter with a voltage divider to check the voltage of the output. If the voltage is low, try using a different transformer. The transformer windings could be damaged.
Step 4: How This Circuit Works
The working principle of this circuit is very simple. I have described in a few steps:
- When you apply a power source, the current flows from the feedback coil to the BJT through a resistor. This turns on the primary coil.
- When the primary coil is on, a voltage is induced in the feedback coil. When the feedback coil is connected correctly, the polarity of the coil is opposite to the battery. When this happens, The net voltage at the BJT gate is zero or negative, which means no current flows. This turns off the BJT.
- This cycle repeats very fast, at tens of kilohertz which make dc pulses at the output of the transformer
Step 5: Done!
If you have finished till this step, you might have made your own Tiny High Voltage Power Supply. You can now use this to power all kinds of high voltage electronics, keep in mind that the current will be low.
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