OK, time to jump on the oscilloscope clock bandwagon! It's an old idea, but they just look so cool.
This was going to be a simple clone of some rather simplistic transistor-based designs around the internet, but now I've got something more ambitious in mind! Here's the prototype in action:
- 3BP1(A) CRT with proper drive to +360/-1400V pcb
- Tube-based deflection circuit using 6SN7 or 12SN7 dual triodes pcb
- Voltage-multiplier HV supply using an Antek transformer
- Display-list based vector graphics generator (or could cheat and use a uC)
The CRT circuit is directly inspired by Steve Anderson's narrow-bandwidth TV (NBTV) monitor design, as found at https://www.taswegian.com/NBTV/forum/index.php.
Status
2021-01-14 - Rev A tag after DAC PCBs and parts ordered.
Now looking at the power supply.
2022-12-28 - more or less working. Hand-wired high voltage supply. CRT PCB and deflection amp working with only a couple of tiny issues.
Open issues:
- Deflection amp gets quite non-linear at around 60% deflection (-1600V on CRT). At -800V it's fine. Low end of diff output leg is around 250V. The range 250-320 works well.
- If you switch off all the supplies together the CRT arcs inside (oops!). Need to shut down the -1500V first and wait many seconds, then turn off the others. Really need to figure out some sort of shutdown circuit
- The input has to be driven by a laptop.