550V Megger
VR1 - Voltage adjust. VR2 - Calibration adjust. An EI14 (600 ohm) audio transformer (800 turns: 800 turns) could be adapted for the project.
Slight shock hazard, hands away.
Upgrade Your Home Electrical Toolkit with a DIY Insulation Tester!
Tired of relying on expensive or unreliable insulation testers? Take control of your home's electrical safety with this easy-to-build, 550-volt model! Perfect for DIY enthusiasts and professional electricians alike, this project offers:
Safety first: Poor insulation can lead to fires. This tester helps you identify potential problems before they escalate.
Affordable alternative: Skip the price tag of commercial units. This tester uses readily available components for a fraction of the cost.
Easy to use: Push-button operation and clear instructions make it accessible even for beginners.
Versatile: Not just for home wiring! Use it for electronics testing or even measuring dampness in walls.
SETTING UP
Once the circuit has been built, it is first of all necessary to establish the working of the oscillator.
Short the test clips together and the meter should indicate some value. If no movement is seen the oscillator feedback winding (L2) has to be reversed. Once the circuit is working, the output should be set to 550 volts. Connect a high resistance voltmeter between points A and B then adjust VR1 for 550 volts. During this operation the test clips must of course be open circuited. The meter can now be calibrated in terms of megohms. Remove the meter from its case and place it on the working surface having previously cleaned up and dusted down. Carefully remove the scaleplate and paint the reverse side matt white with emulsion paint. When dry place the scaleplate — with its original markings uppermost—on a piece of cardboard. With a compass find the radius of the scale line and the maximum and minimum positions. Transfer these lines to the blank side. Screw the scaleplate back on the meter. Short out the test clips and mark the scale with a soft pencil at this point. Now connect 1, 3, 10 and 50 megohm resistors and mark these equivalent points in. A professional job can be done by using plastic film ink for the scale lines and Letraset for the letters and numbers.