Safety warning! If you do this, wear goggles and rubber gloves. Dispose of the aluminum sulfate solution in a safe and ecological manner. And, do use a corrosion and heat-resistant container. Pyrex is ideal.
SY,
Thanks, I will try this one day, as I can remove each part of the sinks without dismanteling all the amplifier.
I have one more question for Nelson:
The output voltage for the finals are 2* 39 volts, no load.
The output voltage of my circuit is only 2*49 volts for the preamp ;
I would need a few more
ie :52.0 volts
in the A75 Power supply schema here after
I read that the differential amplifier had 5.5 gain so 9.1 zener diode gives
5.5 * 9.1 = 50.05 volts
How could I simply modify the circuit gain built with the original values to reach 52 volts ?
I don't know any thing about diff's
Alain.
Thanks, I will try this one day, as I can remove each part of the sinks without dismanteling all the amplifier.
I have one more question for Nelson:
The output voltage for the finals are 2* 39 volts, no load.
The output voltage of my circuit is only 2*49 volts for the preamp ;
I would need a few more
ie :52.0 volts
in the A75 Power supply schema here after
I read that the differential amplifier had 5.5 gain so 9.1 zener diode gives
5.5 * 9.1 = 50.05 volts
How could I simply modify the circuit gain built with the original values to reach 52 volts ?
I don't know any thing about diff's
Alain.
Attachments
Nice work
Looks like a lot of good info on tapping did arise. My experience is similar to others: Good fluid, use a tap only in the same type of metal, the first time you feel it even have a hint of a bind, throw it away. $5 on a tap is much better than the 10 minutes of profanity after it breaks!!!!
Most importantly, though, keep up the good work and get to other projects soon. I like very much the quality of what you've done.
Sandy.
Looks like a lot of good info on tapping did arise. My experience is similar to others: Good fluid, use a tap only in the same type of metal, the first time you feel it even have a hint of a bind, throw it away. $5 on a tap is much better than the 10 minutes of profanity after it breaks!!!!
Most importantly, though, keep up the good work and get to other projects soon. I like very much the quality of what you've done.
Sandy.
Alain Dupont said:
How could I simply modify the circuit gain built with the original values to reach 52 volts ?
Try to play with R10 (2k2). The simplest way would be adding a parallel trimpot (100K or so) and see what this does.
Also, under the load your rails might go lower than 49V so maybe what you are getting presently at front end is high enough?
Peter,
>Try to play with R10 (2k2). The simplest way would be adding a parallel trimpot >(100K or so) and see what this does.
I appreciate, my knowledge of diff's and digital circuits is near the grass!!
I am here to learn a lot.
>Also, under the load your rails might go lower than "39Volts" so maybe what
>you are getting presently at front end is high enough?
In fact they will because of the 0.5 Ohms 20watts of the CRC's
I just wanted a little more security. and 50/52 volts sounds good to me !}
Thanks.
Alain.
>Try to play with R10 (2k2). The simplest way would be adding a parallel trimpot >(100K or so) and see what this does.
I appreciate, my knowledge of diff's and digital circuits is near the grass!!
I am here to learn a lot.
>Also, under the load your rails might go lower than "39Volts" so maybe what
>you are getting presently at front end is high enough?
In fact they will because of the 0.5 Ohms 20watts of the CRC's
I just wanted a little more security. and 50/52 volts sounds good to me !}
Thanks.
Alain.
Peter,
The finals 2 power supply's gives 2* 45 volts with "no load",
I had to replace the 6amp fast blow fuses ; they blew up ; but 10 amps are OK now...
I have soldered 75 K ohms in // with R5 and R10
which gives 50 volts for the pre.
Do you think it's enough ?
Regards,
Alain.
The finals 2 power supply's gives 2* 45 volts with "no load",
I had to replace the 6amp fast blow fuses ; they blew up ; but 10 amps are OK now...
I have soldered 75 K ohms in // with R5 and R10
which gives 50 volts for the pre.
Do you think it's enough ?
Regards,
Alain.
I don't remember exactly, was it 5V or 10V difference between output rails and front end supply.
As to the blowing fuse, are you using any thermistors on primary?
With such big toroids and so many capacitance it's nothing unusual. Even with thermistor, I was using 10A fuses.
As to the blowing fuse, are you using any thermistors on primary?
With such big toroids and so many capacitance it's nothing unusual. Even with thermistor, I was using 10A fuses.
I just checked: the front end should be 50V and output stage 40V.
So how much you are getting on rails under the load? I think it shoul be close to 40V, so you should be fine.
So how much you are getting on rails under the load? I think it shoul be close to 40V, so you should be fine.
Peter,
Thanks , I go with these values. I think the voltage will drop of 4/5 volts under load.
I will install the mosfet's on the front end tomorow,
and let the fun begin...
Now I am willing to finish the cabling of the standby relays
Thanks for the fast reply.
Regards.
Alain
Thanks , I go with these values. I think the voltage will drop of 4/5 volts under load.
I will install the mosfet's on the front end tomorow,
and let the fun begin...
Now I am willing to finish the cabling of the standby relays
Thanks for the fast reply.
Regards.
Alain
Peter,
Tested on right half channel final's power supply (positive only) 38.8 volts
on 10 ohms between positive to ground.
I think it's good. 😉
Regards.
Alain.
Tested on right half channel final's power supply (positive only) 38.8 volts
on 10 ohms between positive to ground.
I think it's good. 😉
Regards.
Alain.
Bricolo,
>> You could use shottky diodes to get 1 more volt.
Thanks, I take that for the next project, at this point of the A-75 ;
my only care is for the Front end PCb, I want to listen Sunday !
A+
Alain.
>> You could use shottky diodes to get 1 more volt.
Thanks, I take that for the next project, at this point of the A-75 ;
my only care is for the Front end PCb, I want to listen Sunday !
A+
Alain.
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