Well, if you are going to use a 6X5 in place of a 6X4, although both valves can handle the same HT current and voltage, you should check the reservoir capacitor. A 6X4 can have up to 40uf, but a 6X5 can only have 8uf, so adapt the circuit if necessary.
If you do have to change the reservoir cap, then the HT voltage under load may change slightly also. I would recommend not to exceed the 6X5's max reservoir rating. In the past the 6X5 was widely used over here as rectifiers in '40s and '50s valve radios, and I've come across several over the years in which the rectifier failed, in one case shorting out the mains transformer and causing a fire inside the set, and the one thing in common with these sets is that someone at some time had replaced the reservoir cap with one of a much higher value!
If you do have to change the reservoir cap, then the HT voltage under load may change slightly also. I would recommend not to exceed the 6X5's max reservoir rating. In the past the 6X5 was widely used over here as rectifiers in '40s and '50s valve radios, and I've come across several over the years in which the rectifier failed, in one case shorting out the mains transformer and causing a fire inside the set, and the one thing in common with these sets is that someone at some time had replaced the reservoir cap with one of a much higher value!
I'm not exactly going to use 6X5 but a 6X5GT. I looked into the datasheets I downloaded from Frank's. I can't find any mentioned
of 40uF for the 6X4.
I found a spec called "Capacitor input filter". It mentioned 20uf for the 6X4 and 4uf for the 6X5GT.
I really don't understand much how reservoir capacitor works so
if you could help me modified this circuit (http://home.swbell.net/acavalli/images/MJ_Power_Supply_2.gif) to suit a 6X5GT, I would be most grateful.
Thanks
jayel
of 40uF for the 6X4.
I found a spec called "Capacitor input filter". It mentioned 20uf for the 6X4 and 4uf for the 6X5GT.
I really don't understand much how reservoir capacitor works so
if you could help me modified this circuit (http://home.swbell.net/acavalli/images/MJ_Power_Supply_2.gif) to suit a 6X5GT, I would be most grateful.
Thanks
jayel
Hi Alex,
This is the PSU for a 6DJ8 preamp right?
Anyway, you can use an LC filter instead of the CLC filter you now show.
Suppress the first 100 uF cap... you can put it behind the self if you like...
The 470K R you can put across the last cap where it will serve as a bleeder.
The 100 Ohm resistor can be removed as well, the circuit will have a slow start as it is already.
The 2K2 resistor inbetween the two filter caps may need revision according to the B+ you get.
BTW, are you out the woods yet with the 6DJ8 preamp yet?
I notice you will be using three of them...
Which brings me to the heater supply, if left as shown now you'll be feed the 6.3 V heaters with roughly 8 VDC which way too much.
The "optional" resistor will be required and will need to go up in value to bring the voltage down.
Keep in mind to use one of appropriate wattage for it's going to dissipate close to 10W.
Cheers,
This is the PSU for a 6DJ8 preamp right?
Anyway, you can use an LC filter instead of the CLC filter you now show.
Suppress the first 100 uF cap... you can put it behind the self if you like...
The 470K R you can put across the last cap where it will serve as a bleeder.
The 100 Ohm resistor can be removed as well, the circuit will have a slow start as it is already.
The 2K2 resistor inbetween the two filter caps may need revision according to the B+ you get.
BTW, are you out the woods yet with the 6DJ8 preamp yet?
I notice you will be using three of them...
Which brings me to the heater supply, if left as shown now you'll be feed the 6.3 V heaters with roughly 8 VDC which way too much.
The "optional" resistor will be required and will need to go up in value to bring the voltage down.
Keep in mind to use one of appropriate wattage for it's going to dissipate close to 10W.
Cheers,
Jayal,
I can understand the confusion over reservoir caps - it is not helped by different manufacturers giving different specifications. I have the specs for several thousand valves by different manufacturers, and, for example, Mullard quote 16uf for the reservoir cap of a 6X5GT whilst Tungsram quote 4uf, Cossor quote 8uf and Brimar 32uf! Mullard quote 16uf for a 6X5, but Brimar quote 40uf!
To play it safe it might be wise to veer towards the lower values in your power supply. In the old valve sets I mentioned which used a 6X5(GT) a 8uf was common for a reservoir cap and 16uf for the smoothing cap after a choke.
I can understand the confusion over reservoir caps - it is not helped by different manufacturers giving different specifications. I have the specs for several thousand valves by different manufacturers, and, for example, Mullard quote 16uf for the reservoir cap of a 6X5GT whilst Tungsram quote 4uf, Cossor quote 8uf and Brimar 32uf! Mullard quote 16uf for a 6X5, but Brimar quote 40uf!
To play it safe it might be wise to veer towards the lower values in your power supply. In the old valve sets I mentioned which used a 6X5(GT) a 8uf was common for a reservoir cap and 16uf for the smoothing cap after a choke.
Hi,
5W on its' own, no.
Here's what you can do, assuming a fictitious value required of 1 Ohm/10W you can use 2 2Ohm/5W resistors in //.
BTW, it doesn't have to be a ceramic one, you can probably source 10W or higher wirewound ones?
Most of those have a heatsink that allows you to srew them to the chassis for better cooling.
Cheers,
5W on its' own, no.
Here's what you can do, assuming a fictitious value required of 1 Ohm/10W you can use 2 2Ohm/5W resistors in //.
BTW, it doesn't have to be a ceramic one, you can probably source 10W or higher wirewound ones?
Most of those have a heatsink that allows you to srew them to the chassis for better cooling.
Cheers,
fdegrove said:
with the recommendation of using an LC filter instead of CLC and the removal of 100 ohm resistor, the circuit now becomes:
6X5GT -->> choke -->> capacitor -->> resistor -->> capacitor
Is this correct?
also, do I change the capacitor values with the change to LC?
thank you.
jayel
Hi,
Indeed, it is. You go from CLC to an LCR type of filter.
Quite likely there won't be any need to do so.
Although the values don't have to be that high I don't mind a bit of a "brute force" approach.
You could do a sim on PSU Designer and it wouldn't surprise me one bit if it'd spit out much smaller value caps.
Either way it won't do any damage.
Cheers,
Indeed, it is. You go from CLC to an LCR type of filter.
Quite likely there won't be any need to do so.
Although the values don't have to be that high I don't mind a bit of a "brute force" approach.
You could do a sim on PSU Designer and it wouldn't surprise me one bit if it'd spit out much smaller value caps.
Either way it won't do any damage.
Cheers,
fdegrove said:
Is there any advantage of using LCR to CLC? Also is there anything wrong with the circuit I posted except for the fact that I'll be using a 6X5GT. I know you mentioned removing the 100 ohms and replacing the 470K after the last capacitor. anything else?
Thank you.
jayel
ps. I'm not trying to question your response. It's more like understanding on how you came up with such a response which would help me understand circuits more.
Hi,
Depends on what you're targetting.
The CLC may have slightly better ripple rejection.
You could give it a try but you'll need a DVM at least to see what gives the best results.
Well, there's that cap directly after the 6X5 of course, either remove it altogether or move it after the choke where you can make another RC filter cell.
No problem.
Cheers,
Depends on what you're targetting.
The CLC may have slightly better ripple rejection.
You could give it a try but you'll need a DVM at least to see what gives the best results.
Well, there's that cap directly after the 6X5 of course, either remove it altogether or move it after the choke where you can make another RC filter cell.
No problem.
Cheers,
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