MagneQuest/Peerless Forum

Welcome! Need support, you got it. Or share your ideas and experiences.

Use this form to submit comments directly to the Asylum moderators for this forum. We're particularly interested in truly outstanding posts that might be added to our FAQs.
You may also use this form to provide feedback or to call attention to messages that may be in violation of our content rules.

You must login to use this feature.

Inmate Login

By default, logging in will set a session cookie that disappears when you close your browser. Clicking on the 'Remember my Moniker & Password' below will cause a permanent 'Login Cookie' to be set.

Moniker/Username: The Name that you picked or by default, your email. Forgot Moniker?	Examples "Rapper", "Bob W", "joe@aol.com".
Password:	Forgot Password?
	Remember my Moniker & Password ( What's this?)

If you don't have an Asylum Account, you can create one by clicking Here.

Our privacy policy can be reviewed by clicking Here.

Inmate Comments

From:
Your Email:
Subject:

Message Comments

Original Message

RE: First Simulation

Posted by jdrouin on March 13, 2017 at 18:06:45:

Thanks, Gordon. Several members at diyaudio helped me figure out that the datasheet numbers for, say, plate voltage actually mean plate-to-cathode. So, the 350V operating point actually requires a B+ supply of 435V, which puts 425V on the plate after passing through the 140 ohm primary of the TFA-204, requiring a 1.25K cathode resistor to maintain a 60mA idle current. This combination also results in ~75V on the cathode: 425V-75V = 350v.

So the attached, revised schematic seems to fit the 350V/60mA into 3K operating slot on the WE datasheet.

I've been simming other circuits too, like the Fi Primer 300B, and have been able to come up with a viable power supply based on the resistance across the 300B and the OPT at those voltages (5.8K on the 300B, 1.25K on the cathode, 140R on the OPT = 7190R for the final resistor in PSUD2). It's been cool to see how the results in PSUD2 match the ones I get in LTSpice.

Can't model the power supply for George's amp in PSUD2, though, because his choke is in the ground leg and the software doesn't offer that option. So I think I'll first breadboard a Fi Primer 300B, since it's a little more straightforward, before attempting George's design.

Now that I have a little experience with modeling this stuff, the mathematics in Morgan Jones' book will make more sense, so I've started reading that too.