DIY MOSFET tester

[gootee]

I took your link down because I am no longer selling them. Sorry. But I don't want a bunch of people emailing me about it.

FYI, my kit included over one thousand parts, all of very high quality, and three professionally-made boards. And even if I bought enough of everything for ten or twenty units at a time, the parts cost was too large a fraction of what I could sell them for. I guess I got a little carried away with the last re-design.

[EUVL]

No problem. In fact I should apologise for linking to your product without first asking.

It will be less than 1000 USD.


Patrick

[gootee]

No need to apologize. If I were still trying to sell them I would have been happy about it.

Yours will have a lot better capabilities than mine, which was $780 as a kit or $1200 assembled, in its last incarnation. So maybe you shouldn't limit your pricing ahead of time.

[EUVL]

It needs a PC and a lab PSU, so it is only fair not to exceed your self contained unit.
But yes, the fact that it is driven by a PC leads to many post processing possibilities.

Best regards,
Patrick

[gootee]

Ah, but don't forget that mine also needed an oscilloscope.

Price by value, not cost, and hope the two never meet!

Oh, I went ahead and expunged my ordering instructions and put the link back up.

P.S. I used to sell mine as a 12V-DC-powered unit, only. I think maybe you could sell more of them if they included the power supply and plugged into the AC Mains. After all, almost everybody has a PC. But not everybody has a spare lab power supply.

[EUVL]

Thanks for the tips.

Patrick

[Melon Head]

Originally Posted by gootee

Price by value, not cost, and hope the two never meet!

Don't tell him that.
I'm after a bargain.
Maybe I will learn Chinese after all.

[EUVL]

That is a good investment in any case -- learning Chinese.

But honestly, if you want to measure small signal transistors, you can buy his, or many other testers on the market. If you want to match 50 power transistors at high current (say 2A), there is so much drift in the reference resistors that you cannot really rely on the measurements. Plus that the power supply transistors will get so hot !!!!!!

If you get proper low tempco hardware, dimension them liberally, put in massive heat sinks, double copper thickness PCBs, ..... the price goes up 10~20 times easy. But you have something you can rely on. The cost is not in the ICs, but in the passives, mechanicals, .... OK, the On Semi audio transistors we use for the dynamic power supply (3 of them for the 3 legs) cost quite a bit as well. So you are basically buying 3 very high quality power amps. (Can't use chip amps because they are not designed to operate at DC -- below 10Hz.)

We are basically changing the hardware for our own purpose.
If we sell a few, it's fine. If not, we aren't too bothered.


Patrick

[Melon Head]

The Chinese have too much of our money already.
I like to support small business as long as I can afford it.

[EUVL]

We don't have a business for this.
Just trying to get some financial support for our DIY development.

And if you know the stories, the ones who is making real money from "cheap" Chinese goods are not he Chinese, but the importers, and in Europe the state (import tax). The Chinese goods are cheap (and often nasty) not because the Chinese do not know how to make them good, but the importers are the ones who set the price.

If you know how much some of our high end loudspeaker chasses cost to make, you will be equally amazed. The manufacturer gets way less than 10% of the price the end consumer pays.



Patrick