The viewfinder CRT from this video camera is a bit harder to interface with generate an X/Y input for. While the vertical can be driven with +/- 10V from a function generator, the horizontal requires higher voltages.
As for the modules previously described, this also takes a 5v input ~100mA. A few other lines need to be pulled up/down to get the CRT to start. Wiring is shown below:
The problem with this board that the horizontal requires ~30v, so you need to source this from somewhere. On the board, this is generated by an inductor (bottom right in the image above). The inductor is fed with 5v. There’s a transistor a (Q009) which I think probably creates a path to ground for this inductor causing a short voltage spike (which hits ~30v). This is what appears to drive the horizontal deflection on this board.
Because of the way it’s generated, it’s not possible to re-purpose the circuitry to amplify an input signal to drive the horizontal deflection… so an external amplifier etc. will be required.
Update: This is now working fine with +/- 6v (H?) and +/-3v. Q009 in addition to controlling the H sweep also seems to turn the beam on/off. However… I fiddled with the pot in the top left and everything seems to be working fine. I also removed the inductor… but I don’t think this is necessary. So it was probably working… just dim all the time.
Depending on the drive frequency, you can see the beam cut out. I’m wondering if it’s possible to just leave the beam on all the time, but the HV generator may not be designed to do this….
I was tearing down a Handycam and came across the viewfinder CRT. I have another project were I want to drive a CRT with an XY input and figured it would be good to experiment with this CRT module. These are my notes.
Here’s the module extracted from the camera:
The module has a 4pin cable which connects it to the camera body. The module requires 5V power at ~60mA.
I fiddled around a bit to determine where power needed to be connected. The connector below the camera side. Clearly at least one of these pins should be signal input (my guess is the yellow wire). But the signal appears to need to be high/low to power up the module.
Below is the setup I used to drive the coils. I drive the coils directly from a function generator. 12Khz +/- 10V works well. The coils are essentially isolated from the rest of the circuit (as I understand it).
Fiddling with the pots on the module can help tighten the spot size, reduce the intensity. Below is a typical video. Couple of 12KHz +/- ~10V sine waves.
I picked up a Panasonic SJ-MR100 for 100 Yen in Akihabara about a year ago. It was sold as junk and came with no accessories. I figured it might be fun to play around with, and I have some minidiscs I recorded a few years ago I wanted to try.
The player/recorder came with no battery/charger. So I hooked it up to a bench supply. I used the internal “gumstick” battery terminals. You can hook the positive supply to the door and ground the internal part of the case. Not ideal, but works for testing. I used about 1.4V. 1.2V will trigger the low battery warning. It draws quite a bit of current when spinning up the motor, so a current limit of 700 or 800mA seems to be required.
When I tried my first few minidiscs they appeared to be playing, but there was no sound. At first I thought the drive was faulty. However, I now suspect this is because they were recorded as MDLP (I don’t know for sure, but I vaguely remember that I used MDLP frequently). The SJ-MR100 was released prior to the introduction of MDLP. It seems to try and play the disc but no audio is produced. The display shows the following (LP, mono):
During normal operation the display is as follows:
My name is Nava Whiteford. I’ve worked for a few sequencing companies. I have equity in a few sequencing companies based on my previous employment (I try to be unbiased in my posts). You can contact me at: [email protected]
RSS