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Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
I am sure that R1= 1M and C1=220nF because I have the circuit board in front of me. What do you suggest the correct values should be ? The LED lamp appears to be one of the cheap unbranded types. The LED's are fitted in a plastic circle, imagine the letter O with the LED's fitted around the...
Hi
I need to repair an AC powered white LED table lamp. The AC mains voltage is 230Vrms. The LED's are a single string of 40 white LED's in series. When I switch it on all the LED's light extremely dimly and show a rapid steady flicker. Maybe it is 25Hz flicker, I really do not know
I...
I need the datasheet for an obsolete ST1720 transistor. I have searched all over the net but have not been able to locate it. Could some one suggest an equivalent transistor ? A project that I want to undertake uses this transistor.
Ericgibbs, a number of the circuits that I want to prototype ( most of them are audio power amps, though not all) require supplies dual polarity supplies +/- 35Vdc at 2A. I gave upper limit of 5A. They are all discrete transistor based designs from Phillips design audio amplifier design book. Do...
Hi
I am looking to build a dual polarity power supply for prototyping my projects. I am looking at
a variable output voltage of +/- 0 to 40V DC, max current drawn 5A DC. Does anyone know any circuits that can do this ? I was searching for RC4194 based designs and LM317 / LM337 based...
I also came across this link. It shows a modulator which can take a
luma + chroma and give a composite out. I think it has a poor performance, though. It was used in the video output of the Commodore 64 computer (very old!)...
thanks, I'll try it out. I assume it works with a PAL signal. One more question. How can I determine if my TV can handle AC or DC coupled signal ? I've not worked with video circuits.
Your circuit will be a lifesaver for a lot of people stuck with S-Video
outputs but only composite inputs on...
Hi
I need to connect a S-Video out from a PC graphics card to my TV
but my TV has a composite in only. Is there a circuit which I can build that
will do this conversion ? Can somebody point me to this ?
olcal
No, I dont think you can use a buffer. One other alternative is to use SMD devices (expensive and difficult to work with for the hobbyist) since small size is a prime concern for you. You could also try quad optocouplers (4 optocouplers on one chip). There doesnt seem to be any way of getting...
I was referring to capacitance and inductance since these are the parameters I am interested in. Is there any difference in capacitors & inductors fabricated for RF and non-RF circuits or are they the same?
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