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After attempting to power up the HeNe tube, carefully short the two output wires of the PSU together (with something insulated); you should get a spark. If not, the psu is probably not working.

Honestly it's not a huge deal, most TECs don't require any kind of unreasonable gain from the opamp so noise and such is usually pretty low especially with the capacitance on the input of the amp.

Yep, I wish their bootloader was open source, the freescale chips are much cheaper than the higher end Atmel stuff

It's more likely than you think ;) For the Scientech 36-5002T2 anyway. This project started as a request that saw my past involvement with LPMs and asked if it was possible to add datalogging to his LPM he ordered from Daguin. I agreed, imagining adding a board I had originally designed for a...

That's good then! Glad to hear it's lasing, what ended up needing tweaking?

The tube can't really overheat if it doesn't ignite first :whistle: Usually there's a bimetal temperature cutout switch in the head that will cut the main interlock if it overheats. This is a problem where the supply isn't producing the normal voltages required to ignite the tube or the igniter...

One thing to note, see the dark stripes down the bore of the tube? Those HeNes have seen quite a lot of use.

Try to reflow those solder joints, they are probably only sufficient to hold the components on the board and will likely result in intermittent operation. Maybe buy a soldering practice kit before you attempt an LPM? Good soldering technique is essential to avoid troubleshooting headaches down...

Re: PERMANENT THREAD: Ebay& other internet FINDS of interest- read all the OP please Spectra Physics Power Meter 407A with Head | eBay Sensor surface looks ok from the poor quality pictures, could be a good deal if you can verify its calibration with a known good meter

Re: PERMANENT THREAD: Ebay& other internet FINDS of interest- read all the OP please That resonator structure is very heavily built, quite impressive

Re: PERMANENT THREAD: Ebay& other internet FINDS of interest- read all the OP please It may be for an older Coherent meter or an OEM product. Either way it could be integrated into existing LPM solutions with a bit of electronics knowhow. Point is moot though since the sensor is damaged. Some...

Re: PERMANENT THREAD: Ebay& other internet FINDS of interest- read all the OP please They just relisted it, looks like there is some ablation on the center of the sensor although it's hard to tell with the crappy photos. I'm gonna pass on it. An awesome deal though if it were undamaged.

They say pictures explain better than words, right?

Hopefully your KnC miner will give a better return than my BFL SC units have :(

Thermal paste is not an effective heat transfer medium... It is designed only to fill the tiny gaps between two metal surfaces. Its thermal transfer properties are extremely poor compared to aluminum/brass/copper/etc. You will likely need better heatsinking than the bare module if you plan to...

Assuming your supply voltage of 9v and a diode forward voltage of 4.25v, the regulator will be dissipating 8.55W of heat to run the diode at 1.8A. With no heatsinking the regulator will quickly reach thermal shutdown temperature and your laser will dim/flash as the regulator protects itself...

Yup, even working HeNes exhibit this behavior. The tube itself is a capacitor (two electrodes separated by an insulator) The zap is usually bigger for tubes that don't ignite since you get the full starting voltage of the HeNe psu instead of the operating voltage (2-3x lower)

This is typical for chinese made drivers, it lets them use the same driver for lasers that do not have any control systems. There is a pullup resistor that keeps the laser on with floating input (this is normally considered unsafe so most higher quality laser systems have pulldown resistors to...

Check out the LM350 instead, you will still need heatsinking

I would recommend staying away from the glass and tube seals when you're trying to zap the tube, this is where you can pierce the tube with the electrical discharge. What you want to do is remove the top cover of the laser head and zap the heatsink that surrounds the bore (do this while the...