Use the tap that you will connect your speakers and adjust the FB by yourself.Maybe you will prefer better another amount of FB. 😉
EC8010's CCS
Hello EC8010,
Your explanation for the scribbled CCS was splendid. I have been looking for a suitable CCS to use for the simple el84 circuit (http://diyparadise.com/ecc99el84c.gif) and I think I have finally found it in your post. I chose the diyparadise el84 pp circuit because it seems to be an ideal first project and they have a mod for using a third el84 as driver (ala sakuma) which I like.
Unfortunately, as splendid as your explanation was, this being my first project and first post on this excellent forum, I am still learning how to walk and so I ask for your kind indulgence if I still missed it.
My problem is how do I replace diyparadise's CCS with your CCS passing 70mA to that 500 ohm pot?
Yours truly,
Sonusanti
Hello EC8010,
Your explanation for the scribbled CCS was splendid. I have been looking for a suitable CCS to use for the simple el84 circuit (http://diyparadise.com/ecc99el84c.gif) and I think I have finally found it in your post. I chose the diyparadise el84 pp circuit because it seems to be an ideal first project and they have a mod for using a third el84 as driver (ala sakuma) which I like.
Unfortunately, as splendid as your explanation was, this being my first project and first post on this excellent forum, I am still learning how to walk and so I ask for your kind indulgence if I still missed it.
My problem is how do I replace diyparadise's CCS with your CCS passing 70mA to that 500 ohm pot?
Yours truly,
Sonusanti
Hello Sonusanti,
here's a CCS for the EL84 amplifier. That 500R variable resistor allows almost any valves to be balanced but drops quite a voltage, forcing the CCS to be deprived of voltage. This might be a problem at higher signal levels, so you might prefer to use a 250R variable resistor or even 100R. I've also changed the 1R2 resistors for 1R so that a DVM reading mV can be interpreted directly in mA.
If you wanted fine adjustment of EL84 cathode current, you could replace the 75R resistor with a 200R variable resistor.
Another trick you might like to try is to note that the cathode of the first valve is at 3.2V, which is the same as the top of the LED chain. You could remove the input valve's cathode resistor (and capacitor) and the 100k 2W resistor and and connect the input valve's cathode to the top of the LED chain so that its current lights the chain. This would save three components and be quite elegant. It might even sound better!
here's a CCS for the EL84 amplifier. That 500R variable resistor allows almost any valves to be balanced but drops quite a voltage, forcing the CCS to be deprived of voltage. This might be a problem at higher signal levels, so you might prefer to use a 250R variable resistor or even 100R. I've also changed the 1R2 resistors for 1R so that a DVM reading mV can be interpreted directly in mA.
If you wanted fine adjustment of EL84 cathode current, you could replace the 75R resistor with a 200R variable resistor.
Another trick you might like to try is to note that the cathode of the first valve is at 3.2V, which is the same as the top of the LED chain. You could remove the input valve's cathode resistor (and capacitor) and the 100k 2W resistor and and connect the input valve's cathode to the top of the LED chain so that its current lights the chain. This would save three components and be quite elegant. It might even sound better!
Attachments
I blanch reflexively when I see significant DC current running through a wiper. Am I just being Chicken Little about that practice?
edit: Is it redundantly repetitive to say "DC current"?
edit: Is it redundantly repetitive to say "DC current"?
No, you're riight, it doesn't do pots any good, but it's unavoidable.
Very few electronics engineers can sign their own name without moving their lips, so the grammarians are unlikely to get you. Anyone for a PC board?
Very few electronics engineers can sign their own name without moving their lips, so the grammarians are unlikely to get you. Anyone for a PC board?
Wiper current
I've found that Cermets mind it less than other types. I can only guess it's to do with local heat dissapation.
I've found that Cermets mind it less than other types. I can only guess it's to do with local heat dissapation.
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