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Old 7th February 2012, 11:39 PM   #1
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Default oneplustwo F5 build thread

Hi folks,

Would you all be interested in yet another F5 build thread? I'm in the middle of collecting parts right now but would be happy to share my progress if there's interest in more DIY amp pr0n!
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Old 8th February 2012, 04:26 AM   #2
6L6 is offline 6L6  United States
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Go for it! Take lots of pictures!
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Old 8th February 2012, 05:39 PM   #3
CENTRAL is offline CENTRAL  Greece
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There's always interest in a nice F5 build. This is a given!
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My F5 is being constructed as we write...
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Old 11th February 2012, 07:26 AM   #4
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No pictures yet... but here's where I'm sourcing parts from so far:

PSU parts:
Mouser Project: link to misc parts
ebay PCB: link (sorry... didn't hear from Pete for a week so I assumed the "real" boards weren't available anymore)
Trafo: Got the shielded one from Antek: AS4218

Heat Sinks:
Got the ones that Antek uses for this enclosure. $25 each shipped with the trafo to help minimize costs (also ordered a B1 trafo and small heatsink.)

The rest of the enclosure will be custom made with 1/4" aluminum plate and perhaps some wooden trim.

PCB and parts from diyaudio store and techDIY
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Old 11th February 2012, 02:17 PM   #5
6L6 is offline 6L6  United States
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Neat! I didn't know you could make a linkable list at Mouser like that...


What circuit do you have in mind with the relay? Looks intriguing!
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Old 11th February 2012, 03:05 PM   #6
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Default AC Coil on DPDT relay: lazy way to control power on AND bleeder resistors

I'm surprised more people haven't used the linkable projects... it's an easy way to share BOMs.

The relay is a lazy man's relay since the coil is designed for 120VAC so all you do is put a switch in series with the relay's coil tabs. Once you make the connection, the relay kicks in and completes the circuit for your transformer primaries.

Also, since you only need an SPDT relay to complete the circuit for the primaries (although I guess you can wire them separately if you had dual primaries... not sure there's any benefit there) you can use the other half of a DPDT relay for something else. In the case of my B24 amp, I use that connection to switch IN my bleeder resistors upon shut down. You can use the SPDT version of the relay if you only need to switch in your transformer of course.

Kinda cool, huh? Makes the wiring a bit messier but the B24 takes forever to bleed down otherwise. That's offset a bit by not needing a separate circuit to control the relay itself though.
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Old 11th February 2012, 06:08 PM   #7
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Originally Posted by oneplustwo View Post
........ You can use the SPDT version of the relay if you only need to switch in your transformer of course.......
Another neat relay trick. If you use a bi-stable latching relay, current to your front panel on-off mains switch only flows momentarily (i.e., the mains switch is a "pushbutton switch"). The relay contacts are engergized when the button is pressed, and are de-energized the next time the button is pressed:

1. Using a front panel "momentary on" pushbutton opens you up to more switch models, and usually costs less than a comparible "on/off" panel switch.

2. Requires a slightly more expensive bi-stable latching relay over a standard relay (but may be offset by the savings in the switch/pushbutton cost).

3. Only flows AC to the front panel when the button is pushed (and not during amp operation). Permits you to group the AC input, fuses, relay and toroid away from audio lines, and not run mains current across the chassis to the front panel). Handy for avoiding potential hum problems.
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Old 11th February 2012, 07:28 PM   #8
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Ooh, I like that even better! Any particular relay you like for this application? I am a little worried about him and the idea of running the relay continuously isn't great either so I'd like to have that as a backup plan.
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Old 12th February 2012, 04:41 AM   #9
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Hey folks,

Quick question for you. Going through my tech-DIY kit and will need to get a few minor items fixed but one question is why there is a P3 200 ohm trim pot? Am I missing something entirely here? Everything else seems to have a home...

Also, on the mosfets, how closely are they supposed to match? They are labeled 427 and 377 (the other kit is 428 and 377). EDIT: never mind... Found the answer. Yay, no matching needed!

Also, got a USPS notice that I missed the antek shipment today (damnit) so will have some pictures hopefully early next week!

-J

Last edited by oneplustwo; 12th February 2012 at 04:49 AM.
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Old 12th February 2012, 10:09 AM   #10
njgale is offline njgale  England
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Originally Posted by oneplustwo View Post
Hey folks,

Quick question for you. Going through my tech-DIY kit and will need to get a few minor items fixed but one question is why there is a P3 200 ohm trim pot? Am I missing something entirely here? Everything else seems to have a home...

-J
Apols if this seems a bit basic.

As I'm still in "learning" mode, I was careful to follow the schematic from the original article linked at the bottom of the FirstWatt F5 page as that was what matched the boards I used (P Daniels initially and then rebuilt onto C Viller V1.1 boards from the diyAudio shop).

P3 was a subsequent additional gift from Nelson, and the latest layout from the F5 Turbo link on the Watts New page is subtly different from the original article and might not match your boards.

HTH

cheers
Nick
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