30-04-2013, 05:12 PM
Many years ago I came across some EHT units.these were voltage multipliers with a 2 transistor oscillator and a toroid.
Input 12V DC, Output frequency 30KHz (and 300V from the Toroid), this was then multiplied up to 20KV for a TV monitor. This was a Marconi design for a broadcast quality B/W monitor. The transistors were BFY51.
Maybe simpler, much cheaper and certainly lighter than the 50Hz iron etc. My Solartron scope uses a 2 transistor Osc too although the output voltage is somewhat higher, this then has a tripler to bring it up to 4KV. Frequency is a bit under 20KHz. and is rather annoying. Certainly at the higher frequencies ripple is less of a problem and the tube capacitance also helps I guess.
Mike
Input 12V DC, Output frequency 30KHz (and 300V from the Toroid), this was then multiplied up to 20KV for a TV monitor. This was a Marconi design for a broadcast quality B/W monitor. The transistors were BFY51.
Maybe simpler, much cheaper and certainly lighter than the 50Hz iron etc. My Solartron scope uses a 2 transistor Osc too although the output voltage is somewhat higher, this then has a tripler to bring it up to 4KV. Frequency is a bit under 20KHz. and is rather annoying. Certainly at the higher frequencies ripple is less of a problem and the tube capacitance also helps I guess.
Mike
