Starting a First Watt F3 build and need some help - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 27th March 2008, 10:37 PM   #1
diyAudio Member
 
Join Date: Feb 2008
Default Starting a First Watt F3 build and need some help

Hello all. I'm getting ready to start a First Watt F3 build and have a few questions about some components. On a scale of 1 to 10 I would rate my knowledge of electronic components at a 3 so take it easy on me. I just want to make sure I'm not buying the wrong stuff.

For resistors I'm using metal film where possible, metal oxide for higher wattage resistors and ceramic where that's all I can find. Is this ok?

For the potentiometers I'm using these. Are these OK?

Family Rotary - Linear
Resistance In Ohms 5.00K
Power (Watts) 0.25W, 1/4W


Will this work for the inrush current limiter?

Family Inrush Current Limiters (ICL)
R @ 25C 15 Ohm
Current - Steady State Max 3A
R @ Current 0.335 Ohm
Tolerance 20%

Is this bridge rectifier ok?

Diode/Rectifier Type Single Phase
Voltage - Rated 200V
Current Rating 35A
Package / Case MB-35
Packaging Tray
Speed Standard Recovery >500ns, > 200mA

Thinking about using this transformer:
AVEL's Y23 series power
Load Capacity: 160 VA
Secondary Voltage: 18V + 18V
Dimensions: 4.0" D x 1.7" H
Weight: 3.3 lbs.

Probably will use a stepped attenuator for volume control. Hopefully it all works out ok. Seems a little overwhelming right now but these projects normally seem to come together with parts in hand. Thanks for any help and thanks Nelson Pass for your great contribution to the DIY community.
  Reply With Quote
Old 28th March 2008, 12:31 AM   #2
MikeW is offline MikeW  United States
diyAudio Member
 
MikeW's Avatar
 
Join Date: Sep 2002
Location: North of Boston
You can get most of the parts from Digi-key or Mouser. You will need a bigger transformer >300 VA or 2 of the 160's. Get a CL_60 thermistor. I have extra if you need one.
__________________
MikeW
  Reply With Quote
Old 28th March 2008, 01:11 AM   #3
diyAudio Member
 
Join Date: Feb 2008
http://cgi.ebay.com/18-18V-400VA-Tor...742.m153.l1262

How does this one look?

400VA 18+18Vac secondaries. Dual 115Vac Primaries.

I can't seem to find a CL60 thermistor on digikey. Does it go by another name?
  Reply With Quote
Old 28th March 2008, 01:34 AM   #4
diyAudio Member
 
Join Date: Feb 2008
I found the CL60 at digikey, Thanks.
  Reply With Quote
Old 28th March 2008, 01:54 AM   #5
diyAudio Member
 
Join Date: Feb 2008
Also thinking about picking up this heatsink and running a bandsaw through the middle. Seems like it would be almost perfect.

http://cgi.ebay.com/Heatsink-LARGE-a...QQcmdZViewItem
  Reply With Quote
Old 1st April 2008, 01:56 AM   #6
diyAudio Member
 
Join Date: Feb 2008
I have been making some more progress on getting all of my parts together. Picked up a 400VA transformer and tracked down the LU1014's. I decided that I'm going to build the heatsink out of some aluminum stock I have lying around.

On the F3 schematics it says that the R5 is matched to the JFET. How do I do this?

Also, how do I adjust the 5K trim pots?

One other question, on the stepped attenuator for volume control, I should match that to the output on the CD player correct? Which in my case is 50K.

Thanks
  Reply With Quote
Old 1st April 2008, 02:06 AM   #7
MikeW is offline MikeW  United States
diyAudio Member
 
MikeW's Avatar
 
Join Date: Sep 2002
Location: North of Boston
http://www.passdiy.com/pdf/ZV9.pdf
The answer to all your questions are here.

Do not underestimate the size of your heatsink. The ones I have are 11 inches x 11 inches x 2.5 inch fins.
__________________
MikeW
  Reply With Quote
Old 1st April 2008, 02:41 AM   #8
diyAudio Member
 
Join Date: Feb 2008
This is what I had in mind. How hot do yours run? Have you measured? Thanks for the link!

Click the image to open in full size.
  Reply With Quote
Old 3rd April 2008, 02:21 AM   #9
diyAudio Member
 
Join Date: Feb 2008
Bear with me here. I've been reading the Z9 manual but it only has 1 5K pot in the circuit. The F3 has two and one more IRFP240 than the Z9. Do I measure the drain on Q5 and then adust P2 until the drain on Q3 is half? I am rather confused and don't want to smoke anything.

Thanks for clearing this up.
  Reply With Quote
Old 3rd April 2008, 03:01 AM   #10
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
The extra Mosfet in the F3 is the power supply regulator.
The extra pot is for trimming the gain of the current source.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Starting a Simple SE build... oldmanStrat Tubelab 75 29th April 2009 02:05 PM
Heathkit AA-151 for starting my first DIY build??? bbaker6212 Tubes / Valves 1 27th August 2002 11:27 PM


New To Site? Need Help?

All times are GMT. The time now is 12:44 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2