I have an single ended amp I'm working on that reuses a power transformer from an old rca-rs188 console. I'm in the planning filter stages using psud2 and I'm wondering what I should expect voltage wise in my new circuit.
The HT is rated at 290 volts @100ma after the 5y3 with an 80uf E-Cap. (No filter network) according to the original schematic.
What I've measured is
Primary-4.32 ohms
Secondary-80 ohms per leg unloaded 302 volts 604 total.
The heaters are also running hot a 7 volts. (Unloaded also)
The new design calls for a b+265v.
Edit From what I can gather a NOS RCA ny3gt has a voltage drop anywhere from 20 volts to 50. (At what current I'm not sure)
My original prints say 290@100ma and I'm getting 302 unloaded. That's not as big of a voltage drop as should be expected.
The HT is rated at 290 volts @100ma after the 5y3 with an 80uf E-Cap. (No filter network) according to the original schematic.
What I've measured is
Primary-4.32 ohms
Secondary-80 ohms per leg unloaded 302 volts 604 total.
The heaters are also running hot a 7 volts. (Unloaded also)
The new design calls for a b+265v.
Edit From what I can gather a NOS RCA ny3gt has a voltage drop anywhere from 20 volts to 50. (At what current I'm not sure)
My original prints say 290@100ma and I'm getting 302 unloaded. That's not as big of a voltage drop as should be expected.
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I know. The original console used that 80uf cap for who knows how long and since then I've used that rectifier in another design paired with 47uf and it worked for years.
I'm not sure what you're asking??? . . . Just plug your PT specs into PSUD, configure the PS as shown in the schematic, use Ohm's Law to calculate the current draw and PSUD will TELL you what to expect.
That's what it does.
The massive thread about that amp is here:
https://www.audiokarma.org/forums/i...ore-out-of-the-8600-series-a-lot-more.665735/
I expect there is some mention there of the specs of the stock Magnavox PT if you want to see how it compares to the RCA PT you're using. You'll likely get plenty of help if you post questions there too. It's a very active thread so rather than starting two threads about it here, why not ask there?
As Dieter said, the first cap is too large, for the DC voltage you're shooting for a value of maybe 10 or 15 uF would be about right. This smaller value will give you a lower DC voltage but with more ripple, so you'll want more capacitance in the filter cap after the choke.
DC voltage from your power supply decreases from a maximum of 1.414 times the transformers's RMS loaded voltage, call it about 300 VAC, for an extra super big capacitance and ideal rectifiers, down towards a value of 0.9 times the RMS loaded voltage (where you have a choke input filter) for no capacitor at all.
PSUD will calculate this for you, or you can just try some values you might have on hand. You must test with the expected load.
These old power transformers were made for the lower mains voltages of their time, and secondary voltages will be proportionally higher today. Heater secondary voltages must be tested with load to be accurate enough to matter.
All good fortune,
Chris
DC voltage from your power supply decreases from a maximum of 1.414 times the transformers's RMS loaded voltage, call it about 300 VAC, for an extra super big capacitance and ideal rectifiers, down towards a value of 0.9 times the RMS loaded voltage (where you have a choke input filter) for no capacitor at all.
PSUD will calculate this for you, or you can just try some values you might have on hand. You must test with the expected load.
These old power transformers were made for the lower mains voltages of their time, and secondary voltages will be proportionally higher today. Heater secondary voltages must be tested with load to be accurate enough to matter.
All good fortune,
Chris
