Insulation Tester power supply - del50001
This is a Inverter Power supply that generates a Precision High
voltage of 100V to 1000V. The voltage is low ripple and High
Regulation and extremely Stable.
Reverse Bias Leakage Tester
One of the earliest Instruments i designed, built and sold in
the 80s. A Digital Insulation tester that helps evaluate
polarization index in transformer insulators.
With these circuits you can make an insulation tester going upto
one tera ohm, 2 Tera ohm max. hence currents will be in pico
amps, great care required in design. Also 1000 Volts DC is
generated which can cause injury. take great care. the above
circuit is for the advanced instrumentation hobbyist only, do
not try it at home.
The parts list which is not in the circuit is listed below, the
circuit is many years old. but you may get some idea on high
Oscillator Circuit Design
The parts list is from my memory, hence it may be wrong, i have
forgotten this circuit, also note the technology may be
obsolete, but basic idea is still the same today.
IC7 IC9 NE555 timer LM555
IC8 LM723 regulator LM723
- Voltage Regulator
Theory of Operation.
IC7 555 as an Astable chops the DC with T2 NPN transistor. TR2
was a Russian U Core High-Freq Transformer. The secondary was
insulated with mylar, layer to layer and impregnated in
Mica-Lacquer or varnish. The 723 Chip along with T1 is The
closed loop regulator which changes the DC which is chopped.
This is part of an old product of mine, it is a megger, a tera
ohm meter or call it an insulation tester. IC8 is LM723 - Voltage Regulator
Voltage to Current Convertor using LM723
The LM723 works like a closed loop Regulator but its DC output
from T1 is chopped by a 555 and T2. This is stepped up by
a small transformer (Russian U Core, with layer to layer
insulation) as it has to meet with near 2KV spikes at output at
Two diodes are used as 1K is the limit of 1N4007. A switching
diode like FR105 may be better. The caps are piled up due
to the high voltage. The feedback is an attenuated sample of HV
output thru the R8 4.7M.
The high voltage current is low for safety reasons, but great
caution has to be taken. TR1 must be a 1 A, 10-0-10
The high voltage is attenuated and that is the feedback to 723
chip which by comparing to a reference, controls the output. The
diodes and caps are in series to withstand 1000V and above.
Back to Insulation Tester