1U5 amplifier design, Newbie - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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
Thread Tools Search this Thread
Old 3rd May 2009, 03:11 AM   #1
diyAudio Member
Join Date: Oct 2005
Location: Benicia CA
Default 1U5 amplifier design, Newbie

I making an amplifier using a 1U5 battery operated tube. Being a Newbie I'm a little baffled. Looking at my test circuit #1, I am getting about -0.5V dc on grid 1. If change R1 to 10K the voltage drops to about -0.05V or so and the voltage on the plate drops to about 30V. Where is this voltage coming from and how do I deal with it? I want to keep the input impedance high so I can use a small decoupling capacitor C1.
Also, can I make the tube behave more like a triode by using circuit#2 or circuit #3? Thanks for your help.
Attached Images
File Type: jpg 1u5ckt.jpg (63.4 KB, 194 views)
  Reply With Quote
Old 3rd May 2009, 06:06 AM   #2
diyAudio Member
jerluwoo's Avatar
Join Date: Feb 2006
Location: Ashland,Ky U.S
Grid leakage would be my first guess. A mere 5 microamps will give you the .5 volts across the 100k. Have you tried more than just 1 of the tubes in the same circuit to see if they all have this behavior?
  Reply With Quote
Old 3rd May 2009, 03:22 PM   #3
diyAudio Member
Join Date: Oct 2005
Location: Benicia CA
Yes I have tried a 1U5 and 2 1U4's (very similar tube, in this circuit)
  Reply With Quote
Old 3rd May 2009, 03:32 PM   #4
diyAudio Member
Join Date: Oct 2005
Location: Benicia CA
More info- I have designed tube circuits using 12ax7's and 6sn7's but this is my first try at a battery powered tube. I am guessing that my problems are from the direct heated cathode or maybe the fact that this is a pentode. Anyone seen example circuits using these tubes?
  Reply With Quote


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
post on amp design by a newbie ultraelite Tubes / Valves 24 19th June 2008 03:22 AM
Amp design Newbie help anyone? matt09 Chip Amps 11 7th August 2006 10:27 PM
Newbie Design seekingwisdom Multi-Way 4 27th April 2005 02:44 AM
Anyone willing to help newbie with crossover design? zachary Multi-Way 2 21st November 2004 12:57 AM
Newbie design mikec Multi-Way 7 5th April 2004 02:03 AM

New To Site? Need Help?

All times are GMT. The time now is 01:26 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2