Moderators: Dave Moll, Andrew Davie, Steve Anderson
Steve Anderson wrote:Yes, very simple, it is only AC-coupled, but it will give you a picture.
One thing I will mention - don't use an old transformer that's been kicking around in a damp shed for years - the insulation may not be up to holding off 1500V. Use a brand new one. They are (should be) flash tested at the factory to at least 2.5kV between primary and secondary.
If that insulation fails say goodbye to your laptop...
Steve A.
Steve Anderson wrote:Yep, it should work exactly in the same manner with a magnetically deflected CRT, depending on the CRT's characteristics and the applied voltages you may need more or less signal.
Though it probably wouldn't make that much difference, it may be a worthwhile thing trying a valve/tube audio output transformer also used in reverse. They should have a better frequency response than a transformer designed for 50/60Hz only. But it's probably not going to be that visible. What you've shown so far looks quite good.
Also the turns ratio in the transformer will affect the amount of signal required. With a 240V-12V transformer that's 20:1, a valve/tube output transformer could have a quite different turns ratio depending on the nominal impedance of the windings/tube (valve) operating conditions/loudspeaker impedance.
Steve A.
A few stabs at the calculator later...yer average table-top radio from the 50's may have used an EL84/6BQ5 output tube/valve. To match the tube/valve to the loudspeaker also results in a turns ratio of around 20:1 or thereabouts...
Andrew Davie wrote:That last picture would be Louise Brooks, I reckon.
Very interesting work!
Steve Anderson wrote:Harry, I'm surprised you're getting such a usable signal out of the TL071, it really is almost useless at just 5V...this applies to most op-amps not designed for low voltage operation.
Steve A.
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