Hello everyone !
I found a great Double EL84 Push-Pull amplifier schematic (28 Watts) but my problem is that I can't find adquate power transformer. I need the following :
Primary : 120 Volts / 60Hz (Canada)
Secondaries : 2 X 220 Volts and enough current for 4 EL84 tubes + 12AX7
As for the 6.3V, I can cope with the idea of an extra transformer
Anyone know where I could find this ? Hammond seems to have one with correct voltages but it doesn't provide enough current....
Also, would it be possible to use a switching suppply instead ?
Any information would be greatly appreciated !!!
Thanks !
I found a great Double EL84 Push-Pull amplifier schematic (28 Watts) but my problem is that I can't find adquate power transformer. I need the following :
Primary : 120 Volts / 60Hz (Canada)
Secondaries : 2 X 220 Volts and enough current for 4 EL84 tubes + 12AX7
As for the 6.3V, I can cope with the idea of an extra transformer
Anyone know where I could find this ? Hammond seems to have one with correct voltages but it doesn't provide enough current....
Also, would it be possible to use a switching suppply instead ?
Any information would be greatly appreciated !!!
Thanks !
And there it is !
Hope this helps !
By the way I'm still looking for a Power Transformer for this amp
Primary : 120 Volts / 60Hz (Canada)
Secondaries : 2 X 220 Volts and enough current for 4 EL84 tubes + 12AX7
Oh, by the way, don't forget, the output tranformer has a primary impedance of 4kOhms
Hope this helps !
By the way I'm still looking for a Power Transformer for this amp
Primary : 120 Volts / 60Hz (Canada)
Secondaries : 2 X 220 Volts and enough current for 4 EL84 tubes + 12AX7
Oh, by the way, don't forget, the output tranformer has a primary impedance of 4kOhms
Thanks you very much 
I've attached the reason why I'm looking for a 2 X 220 Volts .
Also :
Should I connect the suggested transformer exactly the same way as on the schematic ? Will the voltage be too high once the two secondaries connected to the two diodes ?
Also, correct me if I'm wrong but I thought that EL84 were drawing around 60mA each. So a 200mA transformer is a bit tight right ?
Thank you !!!
I've attached the reason why I'm looking for a 2 X 220 Volts
.Also :
Should I connect the suggested transformer exactly the same way as on the schematic ? Will the voltage be too high once the two secondaries connected to the two diodes ?
Also, correct me if I'm wrong but I thought that EL84 were drawing around 60mA each. So a 200mA transformer is a bit tight right ?
Thank you !!!
Attachments
Well, there's some ways to learn without looking so stupid
According to the original Power Supply schematic, we're supposed to get around 300Volts DC if I'm correct.
Using a higher voltage transformer implies that I'll get a higher voltage at the output of the power supply. Is there any risk to blow up something ? (my experience taught me that TDA7294 doesn't like little overvoltage).
Also, I guess that I'll need to increase capacitor voltage (previously rated @ 400Volts)
According to the original Power Supply schematic, we're supposed to get around 300Volts DC if I'm correct.
Using a higher voltage transformer implies that I'll get a higher voltage at the output of the power supply. Is there any risk to blow up something ? (my experience taught me that TDA7294 doesn't like little overvoltage).
Also, I guess that I'll need to increase capacitor voltage (previously rated @ 400Volts)
Got another idea.
Why couldn't I use a standard transformer but connected "backward".
By example, this transformer :
Primary : 120V
Secondary : 60V
This transformer has a ration of 2/1
Connected backward (120V connected on the secondaries), we should mesure 240 volts on the primary right ?
Does that make sense ? I saw that once in an hybrid amp. From a low voltage transformer, the guy was able to drive output ICs + high voltage for the preamp tubes.
I'd like to get your impressions. Thanks !
Why couldn't I use a standard transformer but connected "backward".
By example, this transformer :
Primary : 120V
Secondary : 60V
This transformer has a ration of 2/1
Connected backward (120V connected on the secondaries), we should mesure 240 volts on the primary right ?
Does that make sense ? I saw that once in an hybrid amp. From a low voltage transformer, the guy was able to drive output ICs + high voltage for the preamp tubes.
I'd like to get your impressions. Thanks !
Elkaid,
You cannot run any winding at a higher than rated voltage. There are 2 reasons:
1) The core will probably saturate.
2) Even if it doesn't, there are breakdown of insulation issues.
Also, concerning running transformers backwards:
It will work, but there are safety issues to be considered before putting it into service.
Cheers,
You cannot run any winding at a higher than rated voltage. There are 2 reasons:
1) The core will probably saturate.
2) Even if it doesn't, there are breakdown of insulation issues.
Also, concerning running transformers backwards:
It will work, but there are safety issues to be considered before putting it into service.
Cheers,
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.