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Dazza, Have you got any MOSFET tester circuit, or are you building just one at a time? Here is some stuff to look at: http://www.geocities.com/yukselesen/mosfet_tester_project.htm And here is another:

Hi Steven, Nice work Steven. I just want to ask you what do you mean when you mention

Hi Ian, I experimented some time ago with a variable power supply based on a triac-controlled transformer. I tried this curse I wanted to avoid the heat losses created by the voltage drop over the power transistors. A feedback loop secured a constant 8 Volt drop and minimized the heat. It worked very nicely on the secondary side but not on the primary. The problem was excessive heat in the transformer and eventually damaging it. I did not manage to get it to work so I scrapped the project, this is the reason I am interested in a triac or SCR circuit that do not kill transformers. ;-)

Adam, The filament is not very inductive, consider it as an resistive load. You can omit the extra gate at pin 2 just connect pin 2 to neg on your timer circuit. The capacitor should be rated 250VAC. I understand why your relay is broken, a one second on off time will kill any relay quite fast. This new circuit will not be worn out.

They are all easy to find with the good help of Google!

Adam, Not so fast! If you look at the datasheet you see that you need a few more parts to make it work. First a series resistor for the input (or you blow the led inside). And also a snubber circuit to help the triac get the correct gate current and such you can see an example of this on page 4.

Hi Edude, Yes on the secondary side of your PC PSU (5Volt or 12Volt) you can attach a LED if you also add a series resistor for it.

Hi Eric, Please supply some more info. What type of transistor?

Hi Ian, What kind of SCR dimmer do you recommend for such device? The output waveform from the once I have seen does not work any good as input for a transformer. Usually the transformer gets overheated and destroyed since they are an inductive load and thus do not like the pulseshape (waveform) very much. At least this is my experience of dimmer / transformer circuits.

Ian, With a variac you have the same problem it

Hi Adam, You need an optoisolator to safely use the triac here. Something like the MOC3041 : http://www.web-ee.com/Electronic-Projects/data/moc3041.pdf I don

Hi Quantum, It

Dazza, Yes, when the device (pressure transmitter) is mechanically built and we know it

Perry, Welcome to this forum. What you need is a high gain amplifier and a smith trigger.

Yes you can use 250V instead of 50V caps but they are bigger and very expensive. I haven

Dazza, We need to know the output range from the sensor where it is supposed to work (0 to 25psi) or something like that. You have indicated 2.43 to 3.62V, was this the final decision or are there still changes to be done regarding magnets and moving ranges and so on. Until we

Dazza, You have to find a small enough relay to rob the coil from if you really want to have adjustable strength. There are some very small relays out there, the smallest SMD type I don

John, You can

There is nothing wrong with your idea Audioguru, I was just adding an alternative since I am not completely sure what Benn wants. I don

Hi guys, With DC and MOSFETs you can eliminate the

Stuee, Sorry I did not realize that it was one of the projects on this site. For SCR1 you can use 2N5062, 2N5063 or 2N5064. The diodes are any standard 3A.

Darrin, I don

http://pw1.netcom.com/~t-rex/BatDetector.html

Dazza, I hope your pulling my leg here, cause I can

Hi Benn, Welcome to this forum. If you have the roulette circuit you can use half of the LED outputs (5 of the 10) to drive a triac for each of the lamps. Put a switch on each wire to enable individual on/off. Yes the transformer can be used but the electronics must have DC so a rectifier and a capacitor will be necessary.