• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Suggestion on tube for CCS

hey-Hey!!!,
Build one with two tubes. One triode and a pentode. Cascode connection like Gary Pimm designed MOSFET CCS. Pick high gm/high plate Z pentode for the top, and high gain( within plate Z limits as set out by design parametes ) for the bottom triode. This will burn significant amounts of B+, but it can work *VERY* well.
cheers,
Douglas
 

ray_moth

Ex-Moderator
2004-01-27 8:55 am
Jakarta
I'd like about 30 to 35mA, an octal or loctal base, and to drop the least amount of volts possible.

Sounds like you're looking for the type of pentode that would be suitable as the pass-element in a voltage regulator. In Steve Bench's multi-part article on voltage regulation, he uses the EL509 throughout. I'd guess there are others that might be suitable.
 

Ipanema

Member
2004-06-15 10:34 am
KL
i got a piece of EH ECC88 only. Most of the design I saw are either using resistor/tube load. I'm a tube virgin and a cheapskate too :D Do you have any design using transistor CCS for this tube?

If you don't mind, can you help to explain what are the pro and con of using transistor CCS compared to tube? Any link would be appreciated as well.

Thank you.
 
Re: Re: Suggestion on tube for CCS

Bandersnatch said:
hey-Hey!!!,
Build one with two tubes. One triode and a pentode. Cascode connection like Gary Pimm designed MOSFET CCS. Pick high gm/high plate Z pentode for the top, and high gain( within plate Z limits as set out by design parametes ) for the bottom triode. This will burn significant amounts of B+, but it can work *VERY* well.

Do you have any specific tube suggestions?

-- josé k.
 
Re: Re: Re: Suggestion on tube for CCS

korneluk said:


Do you have any specific tube suggestions?

-- josé k.

12BY7 on top, triode-strapped 12HL7 on the bottom. Create a large voltage ref. so a cathode R of a few kOhm can be used at +20 mA. From 12HL7 cathode-plate set the voltage ref. to deliver at least 1.5V grid-cathode( or the pentode cathode to the triode cathode ) . I suppose a 7788 would also make a nice subject for the lower triode valve. Bypass the pentode g2 to its cathode with a good cap, and select a dropping R to get ~30V below B+.

It winds up looking very much like a Pimm MOSFET cascode.
cheers,
Douglas