Will this work? - Page 3 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

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
Reply
 
Thread Tools Search this Thread
Old 5th May 2006, 04:12 PM   #21
Merlinb is offline Merlinb  United Kingdom
diyAudio Member
 
Merlinb's Avatar
 
Join Date: May 2006
Location: Lancashire
The choke bobbin should be mounted at 90 degrees to the power trans' bobbin or it may induce hum in the HT supply. Dunno if you've already done that!
  Reply With Quote
Old 5th May 2006, 04:20 PM   #22
diyAudio Member
 
Join Date: Jan 2006
Location: Kansas
Thanks for the reply. That was one of the things I was unsure of. When you say bobbin, is that the core (laminations)?
__________________
"Make everything as simple as possible, but no simpler" Einstein
  Reply With Quote
Old 5th May 2006, 05:16 PM   #23
Merlinb is offline Merlinb  United Kingdom
diyAudio Member
 
Merlinb's Avatar
 
Join Date: May 2006
Location: Lancashire
Sort of, its the orientation of the internal bar that goes through the bobbin that matters. That forms the axis of the magnetic field.
  Reply With Quote
Old 5th May 2006, 06:02 PM   #24
diyAudio Member
 
Join Date: Jan 2006
Location: Kansas
Gottcha Thanks, Jay
__________________
"Make everything as simple as possible, but no simpler" Einstein
  Reply With Quote
Old 20th May 2006, 05:04 AM   #25
diyAudio Member
 
Join Date: Jan 2006
Location: Kansas
Well, I got the power supply hooked up. I used motor run oil caps and a big old choke that I don't have specs on. I learned alot, but have one small problem. Instead of 430v I ended up with 570 This is without the .13 load, but I'm not expecting much sag out of this monster tranny. I'm going to put together a load (any suggestions on how) and see what I get. I've got it all built on a chassis so I may be looking for some other tube (schematic) that can handle this voltage and will like the 10kohm primary OPT's. Maybe 807's? I don't know if it is feasable to try and drop B+ 120 to 140 volts. I do have another choke.
__________________
"Make everything as simple as possible, but no simpler" Einstein
  Reply With Quote
Old 20th May 2006, 05:15 AM   #26
lndm is offline lndm  Australia
diyAudio Member
 
Join Date: Mar 2006
Location: nsw
You could look at a choke input filter. This will drop your voltage. It may be a little less predictable to design, sim if possible to check for ringing.

If you want to produce a dummy load, divide your desired B+ by your desired current draw for a stage and this gives you a resistance value to use. Apply it to your supply to see whether it drags it down to where you wanted it to be.

Also, multiply the voltage by the current to see what power the resistor will be dissipating.
  Reply With Quote
Old 20th May 2006, 01:14 PM   #27
diyAudio Member
 
Join Date: Jan 2006
Location: Kansas
By my handy ohms wheel it looks like I need a resistor 4385ohms*74 watts. Heres a picture.
Attached Images
File Type: jpg img_3079 (small).jpg (55.6 KB, 79 views)
__________________
"Make everything as simple as possible, but no simpler" Einstein
  Reply With Quote
Old 20th May 2006, 01:41 PM   #28
lndm is offline lndm  Australia
diyAudio Member
 
Join Date: Mar 2006
Location: nsw
Umm <lndm picks up jaw from floor>, thats a large resistor.

Options:
1. Put a couple of 10W resistors in series and only turn on long enough to take measurements.

2. Use a circuit simulator, I like this method.

3. Make use of the fact that valves are resilient. Make best estimates on values, build your circuit, double check it, and switch on. I mean, if you have a large supply voltage, using that to calculate a dropping resistance for the supply (voltage to drop / current), and using the factory spec cathode resistance, you'll probably end up with less than the expected voltage on your devices anyway. Set your multimeter on a critical point in your circuit before turn on and watch it. You might chose the cathode resistor, so you can watch the current, or measure the anode voltage. If for some reason the voltage gets too high, just switch off.

Killing voltage with series resistance can work for a single ended circuit, but class AB draws a range of current and makes the choke input look like a better idea.

I also have 130V to kill. I use some series resistance to protect my rectifier from excess capacitance, I use some series resistance to reduce ripple, I use a choke that has series resistance. I have enough capacitance at the end to make it all good.

BTW, those are nice looking caps
  Reply With Quote
Old 20th May 2006, 01:51 PM   #29
diyAudio Member
 
Join Date: Jan 2006
Location: Kansas
They do seem to be nice caps. I have a supplier at work who sells to me at cost if stuff is for my use. I got them for 6 bucks each. I'm going to do a little experimenting with some dummy loads and see if I have any sag at all on this contraption. The down side to all this is I have to do all the laundry now as my wife refuses to come down into the basement. Oh well. Thanks for the ideas, Jay
__________________
"Make everything as simple as possible, but no simpler" Einstein
  Reply With Quote
Old 20th May 2006, 09:29 PM   #30
diyAudio Member
 
Join Date: Jan 2006
Location: Kansas
Quote:
Originally posted by lndm
You could look at a choke input filter. This will drop your voltage. It may be a little less predictable to design, sim if possible to check for ringing.

If you want to produce a dummy load, divide your desired B+ by your desired current draw for a stage and this gives you a resistance value to use. Apply it to your supply to see whether it drags it down to where you wanted it to be.

Also, multiply the voltage by the current to see what power the resistor will be dissipating.

I misunderstood. The circuit I'm using wants 430v@.13A. I built this light bulb thing to simulate that load. Five 15 watt bulbs. It brought the vdc down to 515 from 582. Now I will try to figure out a resistor value (to put in series with the load?). Thanks, Jay
Attached Images
File Type: jpg img_3081 (medium).jpg (82.1 KB, 58 views)
__________________
"Make everything as simple as possible, but no simpler" Einstein
  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
Would this work ? LesPaulStandard Instruments and Amps 3 4th May 2006 03:14 AM
Will This Work? sousmielie Class D 6 27th December 2005 06:53 PM
It Should Not Work ! f4bok Solid State 3 6th September 2004 06:33 PM
Would this work? JoeBob Solid State 5 18th July 2003 04:40 PM


New To Site? Need Help?

All times are GMT. The time now is 12:47 PM.


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