| Bas Horneman |
| Would it be able to use a CCS where the choke is used in a DRD/Free Lunch/Monkey amp? |
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| Sch3mat1c |
It would also be possible to use two resistors and a cap, which would allow you to do away with all that hot stuff below the output... :scratch: :scratch: :scratch:
Nevermind. Lesse, CCS would be set for driver plate current...but voltage would be absolutely dependent on the driver's characteristics. Bad idea.
BTW that choke has an awful lot of resistance, though I don't know the current...<takes another look>
Meh, 1.5k for 75H, not bad.
Tim |
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| Bas Horneman |
| quote: | | Nevermind. Lesse, CCS would be set for driver plate current...but voltage would be absolutely dependent on the driver's characteristics. Bad idea. |
Is that not the same with the choke? |
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| James D. |
No it's not the same with the choke. The dc current through the resistance of the choke sets the static voltage. That's how Tim calculated the chokes resistance above...
I was pondering how to overcome this problem before answering myself... no inspiration yet. Let's hope someone else can advise...
ciao
James |
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| Sch3mat1c |
You could always make a nice differential servo-control circuit to control the bias to the driver tube, regulating its DC plate voltage. ;)
Tim |
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| EC8010 |
Since the 46 is fairly low mu and low gm, you could get away with a CCS instead of the choke, but the grid bias on the output valve would be dependent on the conditions of the input valve, so it would need stabilized heater supplies and stabilised HT to the first stage. Stabilized heater supplies are easy to do (317 plus a few Rs and Cs). It might be possible to stabilize the Ht of the first stage simply with a neon reference, a resistor, and a capacitor.
To be honest, I'm not sure if it would be worth the trouble (although stabilizing the heaters would probably be worthwhile). |
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| fdegrove |
Hi,
| quote: | | To be honest, I'm not sure if it would be worth the trouble (although stabilizing the heaters would probably be worthwhile). |
More trouble than it's worth, IMHO.
Any particular reason to get rid of that choke, Bas?
Cheers,;) |
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| Bas Horneman |
| quote: | | Any particular reason to get rid of that choke, Bas? |
Hi Frank,
2 reasons:
Curiosity and cost. I was thinking if they use a ccs where a resistor works or a choke, for example a grid leak resistor or grid choke or a CCS will all work there...why not in a monkey amp?
Plus what do I ask my tranny builder for? I want a monkey/free lunch ...type o choke?...I bet you he won't even have heard of it...
or will any 65h/20mA choke do...should I ask for C core / Amorphous or just plain M something?
a ccs however is built in 5min and there you go!
I am planning a 7n7 / 2a3 amp..
Cheers,
Bas |
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| dhaen |
Bas,
Wil will need to know:
The inductance
The current
The DC resistance
After that, I expect he'll wind it just like an output transformer primary: with as many sections as he sees fit.
On a thread last year, Thorsten described a push-pull monkey For that he used an EL84 P-P output transformer with the secondary unconnected.
Cheers, |
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| Bas Horneman |
| quote: | The inductance
The current
The DC resistance |
Aaahh "het kwartje is gevallen" ..meaning now I understand
So it's not so simple after all. I thought I could just take chuck in any old choke of 65/20mA and voila..but you need the voltage to be in the ballpark for the driver tube !!
Thanks John!! Got your mail about you not having mail..but was too tired to answer..last night..when I read it..read why below..
PS
Just got back from Frank's country Belgium we went there as part of our rugby tour! Got drunk on Stella..no fancy beer for me...tour rules required us to wear a skirt...So Frank if you happened to be in Leuven this past weekend and saw some dutch idiots in dresses that was us. |
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| dhaen |
Bas,
I didn't necessarily mean it's not simple. My answer was to your "what to ask for" question.
An anode choke of suitable ratings should do.
Bas,
When on Friday you said you were "putting your dress on" I thought you meant "kit":eek:
Now I know......:cannotbe:
Cheers, |
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| fdegrove |
Hi Bas,
| quote: | | So Frank if you happened to be in Leuven this past weekend and saw some dutch idiots in dresses that was us. |
You're kidding... I live only half an hour away from Leuven.
Next time let me know in advance, I may meet you there.
As for the choke, i think if you show Wil the circuit + the electrical requirements, he'll just wind it for you.
After all, as John pointed out there's nothing magical about this particular choke.
Cheers,;) |
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| dhaen |
Bas,
Did the men in skirts win?
:censored:
Cheers, |
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| Bas Horneman |
| quote: | | You're kidding... I live only half an hour away from Leuven |
Sh*t, should have known..would have been good to drink a couple of beers and talk tubes!
| quote: | | Did the men in skirts win? |
Yes, we won the tournament..!!!! Don't know how we did it, just that we did it...
Cheers,
Bas |
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| dhaen |
| quote: | Originally posted by Bas Horneman
snip..
Yes, we won the tournament..!!!! Don't know how we did it, just that we did it...
Cheers,
Bas |
Congratulations!
Cheers, |
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