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Attempted trial for starting of an FAP800 infrared laser module.

Attempted trial for starting of an FAP800 infrared laser module.

Attempted trial for starting of an FAP800 infrared laser module using materials at hand.

FAP800 laser module by Coherent

The laser powering

The laser under study has a low-voltage power supply (<2.1 V) and a threshold current from 8 to 11 amperes, the operating current, according to the documentation, is <30 amperes. Unfortunately, at the moment we do not have a power supply unit with the needed parameters, so we have decided to try to start the laser using Chinese DC-DC converters and several 12 V switching power supplies with 12V 5A.

Experiment number 1

We use two Chinese DC-DC converters (declared current 10 A), connected in parallel with two power sources.

2 DC DC units in parallel

The main issues associated with this type of connection are:
The inability to accurately balance the output voltages of the converters;
The premature protection operation on one of the converters with the subsequent cascade shutdown of the second converter.

This is clearly seen in the video below (from 0:19):

As a result, a weak luminescence was obtained at a voltage of 1.8 V and a current of about 5 amperes.

Experiment number 2

20 A DC DC step down converter
A 20 A DC DC step down converter

This time instead of two stabilizers connected in parallel, we used another Chinese DC-DC converter. Its design signature is three trimmers. Experience has shown that the converter provides the voltage/current adjustment and the current protection setting when the threshold is exceeded. The stated current is also indicated as 10 A. On the reverse side of the converter there is a radiator of the same size as the printed circuit board.

An FAP800 laser beam
FAP800 laser beam

The results of this test turned out to be better than those of the previous one, apparently, thanks to the absence of the second converter connected in parallel, and, as a result, no balancing currents issues arose. The operating current was successfully raised up to 7.5 – 8 amps, with a voltage of about 1.85 V.

To sum up, it may be said that for the reliable, continuous operation of this laser the parallel connection of DC-DC converters is of little help, if any, and a good power source is needed.

FAP800 laser beam

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