Lab Benchtop Test Instruments
Regulated Power Supply 30V 5A
This is a Regulated 0-30 V DC Power Supply manufactured
by me in
small numbers, 0-30V 5A and 5V -5A. It had a Switching Preregulator.
This keeps the Vce across Transistor Bank at the Back of Instrument, at
the lowest possible level, in order to keep them Cool. When Vce and Ic
both are more in a Power transistor it will get heated more, then the
efficiency of power supply is low.
The Output had both Constant Current Control and
Constant Voltage
Control. The CC control is also a Short circuit protection. The Output
was protected from outside voltages damaging output circuits even when
equipment is switched off. The back panel is a finned anodized black
aluminum heat sink with many transistors.
I looked for the
circuits to scan them, i could not find it. I made-n-sold quite a few
of them years ago. All of them work well even today as i over-rated
most components. The cabinet was Steel for EMI-RFI Immunity, it was
painted with Stipple Matt Powder Coating, the Cabinet maker had just
learnt to give such a finish to his boxes.

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On the right is the catalog i made many years back
to promote the DC Power supply i manufactured.
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Tera Ohm Meter and Insulation Tester
This is a 20 Tera Ohm Insulation Tester I made around 20 Years Back. It
had even Polarization Index for Transformer Insulation. It generated
1000V DC Regulated Voltage and the pA leakage Current was Measured. See
more here Insulation
tester or Tera ohm meter.
A regulated, low ripple, high voltage of very low
current capability
is applied by instrument on a DUT (device under test). The leakage
current in nA or pA (picoamps, nanoamps) is measured and readout, The
Innovation i did was to measure the current in Vref and not Vin of
ICL7107, this made the 1/x computation.
Also using the ICL7650
Chopper Stabilized amplifier must be done as shown in data sheets with
grounded guard rings. pA will leak on the PCB itself if layout is not
done keeping this in mind.
Megger or Insulation Tester
Decades ago, when a customer found that my Tera Ohm Meter expensive, He
suggested the specs for this low cost scaled-down model. This was found
useful for people sub-contracting Telecom Equipment Manufacturing.
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