Driving common source MOSFets with OptoMosfet

I wish I could simply buy 2 1-Form-C SSRs, but in France, they are really hard to come by. And ordering from the US is just too costly (20$ S&H + Customs for two 4$ parts). Hence the desire to replace those with what I get my hands on.

We do, but they don't have Opto Mosfets, or if they do, they don't have the P types. Well, one distributor has one of them, but sold 14.5 euros, it's way too much when you know an equivalent one costs 4$ in the US...

Yeah, industrial types, 20 euros each at least, able to commute 500V at

Well, I tried contacting the manufacturers, but they don't even answer my requests. I guess the hobbyist market is of no interest to them (I can understand that though)

The simple part best suited for your use is available in France, and the rest of Europe. At a reasonable price if you know where to look, I'm sure. That's what you should pursue, in my opinion.

Didn't you read our elementary FET chapter? Or my detailed post on the issue in the last thread? It's depletion mode rather than enhancement mode that's required, and it has nothing to do with whether it's n-channel or p-channel. The popular ones are n-type.

Sorry, this will not work. By tieing both negative terminals of the rectifiers to Vss, you short out parts of the rectifiers. You can only use one of them, not two. You can, however build 2 isolated circuits using two opto-mosfets.

HTH Wolfgang

But then, how do you create a Normally Closed relay ?

Bummer, that means I need 4 of those OptoIsolated drivers... This is very annoying.

When you say, "Don't answer your requests" - that covers a lot of ground. Are they not answering emails? Do you go to their web sites and fill out information request forms? Have you tried calling a salesman or rep on the telephone? Have you written a letter?

There's a way to get stuff - Don't listen to these weenies who are dissing you just 'cuz you're French; but you are the man on the ground on-site, and a little legwork, or even fingerwork ("let your fingers do the walking" - Yellow Pages ad) can go a long way.

I've even told salesmen, "It's just for a hobby project, so I doubt if I'll ever need more than a couple..." and they have sympathy and send me a couple of parts. Usually it's stuff that costs like two bucks to send, and he just puts that on his "dealing with prospects" budget. I even once had a guy who was on a sales call at a company where I was a temp, hand me two, 16-bit ADCs that were retailing at about $25.00 apiece back in those days. He had a sample case full of them.

So, ask around - you never know!

Good Luck! Rich

England has "Radio Spares" - why not just hitchhike over there and pick up some parts? They finally got that tunnel finished, I hear. ;-P

Yeah, I took the chunnel train from London to Paris, first class... had my own steward who cooked breakfast for me. The thing that amazed me was that, when I got to Paris, I just walked off the train out into the street; no customs, no visible security. Cool. That's nice, being able to step onto a train and spend the weekend in another country with no hassles.

John

Yup, and you can drive through a whole bunch of countries without ever being asked to produce documents or a passport, and mostly keep using the same currency. There's security for the train itself though. IIRC they close the "departure" area 20 or 30 minutes before the train actually leaves-- just like an airplane-- none of this dashing through the station and jumping on the train as it begins to move, as I found out to my chagrin. Stuck in Paris for a few extra hours- not such a terrible thing. ;-)

Best regards, Spehro Pefhany

I keep looking, but I look at other options. Thing is, we have Farnell, Radiospares and others, but either they don't even have the part in their catalogue, or they have it but send it directly from the US billing 25euros for S&H. I even tried to call some of them, they sometimes don't even OptoMosfets even exist... That's a pity, I'll have to use a regular relay, less fun, much easier to find.

Bummer. I recently wanted to try a couple AD 2 axis accelerometer chips for use in a tilt sensor project. I went online and asked for samples. Not only did they give me a couple, they arrived at my door the next morning. I could have waited if they had asked.

I know one ham in France who is into high tech construction. You can look at this page

I've mostly tried emails, filled request forms on the manufacturer websites. Got one phone call, but the guy stopped as soon as I said I was a hobbyist. I'd rather not lie to those guys, hence...

I will, ask them about. But there is a "behaviour" within French distributors of electronics component that makes them "despise" hobbyist: They are not worthy of much. But a good hobbyist can convince a company, or work for one and bring in his experience with these components. Ah well, I'll keep those arguments for my next few days phone calls.

Thanks, I'll keep on trying.

Olivier

I obviously has not, as you suppose. Fact is, I don't even know where it would be located. Was that in one of the threads here?

Let me see... Yeah, I read that, but somehow must have "zapped" it. Sorry about that, I'll look for depletion mode FETs

Once again, thanks a lot for your help. Cheers Olivier