JojoD818 said:
a thermistor controlled fan is also something that could be included given the high ambient temps in India. Are the temps in Manila also high?
I would like to also take this opportunity to thank JojoD818, SY, Corbato, Johaan, Poobah, Tony and all those who have helped me so far. I still have a few questions before I start collecting parts.
1. Wattage of the resistors and Voltages of the capacitors in Wayne's schematic
2. Power Transformer details and a SS rectifier schematic.
I am going to use the CCS used by SY and JoJo818. Thanks guys.
navin said:
I posted it before but values are still under research. I'm using PSU designer for the HT psu design. My tranny has 2 separate windings of 6.3V @5A, and a 5V @3A also.
hi navin,
if i were to specify your power transformer it will go something like this:
primary: 230volts, 450va
secondary: main ht. 320vac @1A
bias supply, 50vac @0.1A
heater, 6.3volts @10A
secondary va: 320+5+60=385va
this is more than enough, so in future you can switch to 6550 easy! it is always wise to invest in a good power transformer.😀
if i were to specify your power transformer it will go something like this:
primary: 230volts, 450va
secondary: main ht. 320vac @1A
bias supply, 50vac @0.1A
heater, 6.3volts @10A
secondary va: 320+5+60=385va
this is more than enough, so in future you can switch to 6550 easy! it is always wise to invest in a good power transformer.😀
navin said:
the feedback resistor will not be the same as when you connect it to 4ohm. if you want the input sensitivity to remain the same. if you will be using 8ohm speakers better use the 8ohm tap and adjust it from there.
this is best done with a scope, you can not see the overshoots by using your ear! hehehe!
no, Q1 should be a tip50 (Vbceo=500) and Q2 could be a 2sc945, oor 2sc1815.
no, R11 and R12 are grid leak resistors that connects to the wiper of bias trimpots as illustrated by wayne here http://www.diyaudio.com/forums/attachment.php?s=&postid=509305&stamp=1100080737
voltge across R11 and R12 is zero, you can measure the bias voltage at the wiper arm of the bias trimpot.
your call!
you can use 1n4148, 1n914, my choce is 1n4935 cause i have them
yes, sure.
yes, but 600volts is preffered, mallory 715p's are fine. C2 is not used i think.
i posted above spec for traffo, but if you are to follow waynes' then use the voltage specs mentioned, but i would stick to the va rating.
😀
Tony said:
Great. I told him 500VA so i could get a quote. I had assumed 340 x 0.5A and 6.3 x 10A but doubled it in case I was off. Now I know I was. Thanks!!!!
So using Wayne's PS I should get 340V * 1A + 70V * 0.2A + 6.3V *12A which will give me about 400VA and some headroom.
Tony said:
My woofer are 4 ohms. So i should use the 4 ohm tap right.
Ok so R25-27 are the trimpots. Do those have to be anything special (wire wound or multi turn)?
if Voltage across R11 and R12 is 0 current will also be 0. Now I am confused.
do all caps have to be 600V? The largest i get are 450V DC. How do i get 630V DC. Can I put caps in series for this. say 2* 2uf 315V DV = 1 * 1uf 630VDC.
hi navin,
ask your winder, to intall electrostatic sheilds between primary and secondary windings.
for bias trimpots you can use multiturn if you like, when first powering up, set the wiper arm to the maximum negative voltage.
since your highest B+ is 450volts, i guess ou can use 450volt caps as well.
don't be confused with R11, R12 they are grid leaks and serves as load for the previous stage, af voltage drive to the grids of the EL34 are formed there, at the same time they serve as biasing resistors for the grids. to operate the EL34's Class A or AB1 the grids are biased negative WRT ground.
ask your winder, to intall electrostatic sheilds between primary and secondary windings.
for bias trimpots you can use multiturn if you like, when first powering up, set the wiper arm to the maximum negative voltage.
since your highest B+ is 450volts, i guess ou can use 450volt caps as well.
don't be confused with R11, R12 they are grid leaks and serves as load for the previous stage, af voltage drive to the grids of the EL34 are formed there, at the same time they serve as biasing resistors for the grids. to operate the EL34's Class A or AB1 the grids are biased negative WRT ground.
Navin,
Re my delay circuit. Yes I use a timer, in fact one amp of a general quad op amplifier LM324. It (other circuits round the rest of the 324) also serves as an overload detector/safety circuit activating a relay to cut the 640VAC main power supply. (In an amp using a total of 8 x 6L6GC and a main h.t. of 600V, one needs a quick cut-off when things go wrong, so as not to suffer a jolt to the bank balance!)
Regards and best wishes for your project.
Re my delay circuit. Yes I use a timer, in fact one amp of a general quad op amplifier LM324. It (other circuits round the rest of the 324) also serves as an overload detector/safety circuit activating a relay to cut the 640VAC main power supply. (In an amp using a total of 8 x 6L6GC and a main h.t. of 600V, one needs a quick cut-off when things go wrong, so as not to suffer a jolt to the bank balance!)
Regards and best wishes for your project.
Tony said:
I was not sure this power supply could be used with the schematic Wayne posted on this thread. although wayne did mention that I should look at it in his post 164.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=69042&perpage=10&pagenumber=17
Yes I dont have more than 450V but wayne had specified 630V on 1uf and 100nf caps on his ckt.
Thanks Tony. I'm greatly indebted for this hand holding.
Tony said:
so R25-28 in the power supply ckt are the bias pots and i connect A & B on Wayne's power supply to where is says "Bias" on the R11, R12 on one channel and C & D to R11 and R12 of the other channel.
Thanks Tony. I am a bit confused as to if wayne's power supply from "EL 34 push Pull Ultraliear' can beused with the EL34 ckt he posted earlier and if so how.
Johan Potgieter said:
would love to see a schematic if you have one.
what is the function of the encircled resistor? a technician friend said that it can be omitted but the bias setting (or bias psu) would have to be altered too. I would have removed it but he has no firm explanation as to what the resistor does to the circuit.
the resistor is in parallel with the 0.25 cap.
thanks,
JojoD
the resistor is in parallel with the 0.25 cap.
thanks,
JojoD
JojoD818 said:what is the function of the encircled resistor?
Cant answer that. I am not Wayne, SY, Tony, Johaan, etc.. but I guess if they saw the full ckt they could.
Hi navin,
I cropped the pic so I can emphasize on the resistor. 😀 I figured the whole schematic is kinda big to be posted.
If your interested in the schematic do drop me an email and I'll send em to you.
JojoD
I cropped the pic so I can emphasize on the resistor. 😀 I figured the whole schematic is kinda big to be posted.
If your interested in the schematic do drop me an email and I'll send em to you.
JojoD
The encircled resistor forms part of a step network. I use step networks to couple my 6SL7 splitter to 6SN7 driver. The purpose is to provide low frequency stability for inclusion in an NFB loop, without having to use DC coupling. DC coupling causes a high voltage on the grid of the second tube. In addition, if you are cascading 2 differential stages, any DC imbalance is made worse by DC coupling.
ray_moth said:
so that is waht the C5/R35 is in your ckt. I wondered earlier but kept my mouth shut for fear of sounding like an idiot.
navin,
when your winder in singapore gets back to you with the quote, can you ask him, the EI he is going to use, i mean the center leg width and stacking height. i want to find out if his idea of a 500va transformer is the same as mine.
thanks
when your winder in singapore gets back to you with the quote, can you ask him, the EI he is going to use, i mean the center leg width and stacking height. i want to find out if his idea of a 500va transformer is the same as mine.
thanks
Tony said:
Will do. but my PS winder is not in singapore. Only my OPTs are from there.
However I will ask my winder what size of EI core he is going to use. I would guess the PS tranny would be about as big as my OPT (90mm x 90mm x 110mm Height). Should it be bigger?
yes, i think so. btw, have you finaly decided on which circuit you are going to use? so that we will base discussions from that circuit from hereon.
ray_moth said:
thanks for the help! i just finished tweaking my amp's bias supply and main psu. this amp also has these resistors across the coupling caps between the driver and the opt tube.
regards
Tony said:
oh yes. I am using wayne's 6SL7-6SN7-EL34 schematic as well as the PSU he posted on another thread.
this is the schematic
http://www.diyaudio.com/forums/attachment.php?s=&postid=811638&stamp=1136905599
and this is the PSU
http://www.diyaudio.com/forums/attachment.php?s=&postid=509305&stamp=1100080737
and this is the CCS
http://www.diyaudio.com/forums/showthread.php?s=&threadid=69042&perpage=10&pagenumber=22
do I need anything else. I am eager to go shopping for resistors and caps and a power tranny and oh those transistors for the CCS too!
BTW I intend to replace all 630V DC caps in Wayne's PSU schematic with 450V DC becuase that is what is available here. Any aphrehensions?
hi navin,
you will need a chassis, once you gather all chasiss mount parts, you should consider the chassis, are there sheet metal wood working shops near you?
you will need a chassis, once you gather all chasiss mount parts, you should consider the chassis, are there sheet metal wood working shops near you?
navin said:
You could fry C11 if you'll use 450V only as the voltage during cold starts can reach up to 480V. You can get away with C12 and C13 at 450V though.
Safety First.
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