Converting a B&W TV-set to an Osciloscope.
Converting a B&W TV-set to an Osciloscope.
Excuse me for Grammar errors, I am Dutch.
Well I have done it several times in the past...
Nice to tinker with those!!
It is a VERY CRUDE TIME FIXED scope which draws quite a load from the measured Object, but Hey, you DO get a waveform on the screen!
Lateron I was able to get an good MF Amplifier in the system to Unload the measurement.
Steps on how to do it:
-!!- ALL OF THE BELOW MUST BE DONE WITH POWER DISCONNECTED -!!-
01 Get a B&W television set which DOES still give a raster and a bright beam.
02 Get a deflection yoke from an identical unit (More of it later!)
03 Open the unit that you want to convert, and determine which are the HORISONTAL sweep wires (2) of the deflection yoke.
04 Cut those wires, ( NOT the connections with them!!) and solder them on the corresponding pins of the 2nd Yoke.
05 Get that 2nd yoke as far away from the CRT as possible (Lengthen the wires?)to reduce the influence, preferrably with the business end down / away from the CRT. (If long enough, park it somewhere outside the set.)
06 Loosen the clamp of the yoke on the CRT.
07 Rotate it EXACTLY 90 Deg. clockwise (CRT face facing away!) and reclamp it. (This will convert the vertical 50 / 60 Hz sweep into a Horisontal left-to-right sweep)
08 Solder 2 long wires on the previously empty made pins and led them extend long enough outside the cabinet.
09 Dim contrast and brightness and turn the set on. (Replug the power)
10 Turn the brightness up until you see a nice horisontal sweep.
11 Search for the variable resistor which is ment to stretch the pictuire (Sweep) vertically, and turn it until the sweep fills the whole sceen width.
12 Get a short cirquit proof frequency generator and connect it to the leads you just had soldered on the yoke.
13 Turn it on, play with waveforms, amplitude and frequencies and watch the fun!!!
14 IF you are lucky to find the variable resistor which determines the base vertical timing, (Rolling picture when set wrong in a working unit) you can unsolder it from the PCB and mount an equivalent Potmeter in the cabinet and wire that one up.
This will add some course frequency (timing) control.
IF you happen to have a precision symetrically amplifier of a few watts, solder an 8 Ohm 10 Watt resistor in series with the output and connect that to the set.
Then use the input to measure objects, preferrably inductivly coupled by an Impendance transformer which has > 10K Ohm on the primary to disconnect the grounding lead.
Well, Start rigging, and please sent feedback on how things goes!
Victor.