Bit bored today so as I was going through the experimentalists anonymous forums and I came across the “turn your old TV into an Oscilliscope thread” in the articles and tutorials section.
Basically it’s all there and you simply add a switch and an input to the TV and way you go. I’ve cut the wires and isolated the vertical ones and the horizontal ones but I’ve yet to determine the grounds. I’ll do that tomorrow. What I’ll do as well is isolate where the amp is and fix it so the signal in also goes to the amp so it really is sound and vision. The old TV I’m using was given to me by Blind Shaun and has a radio and a cassette player/recorder so I might have to do something iinteresting with them as well. The tuning for the radio is the old method of changing the capacitance in a tuned L/C amp so maybe I can get a filter of some sort together that will change the capacitance dependant on the signal in. Have to think about that one!
As for the tape maybe I’ll be able to switch the play/record head and erase head wiring so I just have play and record and then just put a loop in the cassette.
I don’t think that normal guitar levels going to do it so getting it up to line level with a booster, what are they called when…thats it, followed by a buffer and maybe even a tranformer coupling for the input as there might be quite a bit of noise on the TV’s earth.
Have Fun… and be careful out there! (remember Hill St Blues?)
Heh, I’d better get up to the tip on Wednesday and find me a little tv.
I guess a little monitor of any sort would work.
Pretty much, I’ve been reading up a bit more and doing measurements and the coils I have are 32ohms resistance so that means a headphone driver amp is whats going to do the job. There was mention of measuring the voltage on the wires after they are cut being in the region of 0-20V so it’s a fair swing but thats the deflection right across the face of the tube so a headphone type amp driving on 15VDC rails would most probably supply enough current and voltage for the tube that I’ve got and looking at the circuit board of the TV theres and couple of reasonably sized power transistors, of the type for driving multiple headphones (say 2-5watts), in the vicinity so they must be the drivers. Maybe one could tap into the base of those because there already set up to drive the coils.
I think each TV will have it’s own needs but the differences shouldn’t be major at all. So maybe I didn’t need to cut the wires and can just go directly into the circuit board. Hmm, I have to look into that. Save building another amp.