Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

Questions for my LM3386 based power-amp.
Questions for my LM3386 based power-amp.
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 22nd December 2001, 03:58 PM   #21
paulb is offline paulb  Canada
diyAudio Member
Join Date: Jun 2001
Location: Calgary
Originally posted by AudioFreak
what i mean is use 2 wall sockets to feed the power box and wire the 2 connectors inside the box together n to n, h to h, g to g so that you have a single n, a single h and a single g inside but fed off 2 wall sockets not one.

It will not give you any sonic benefit whatsoever, and an error in wiring could cause a flash that could cause injury, etc. In addition, some duplex receptacles are wired so that the Hot wires come from different breakers; conceivably, this could be from opposite sides of a 240VAC dual-phase feed, so even proper wiring on your part could cause a short circuit.
If you want to feed your amplifier from two independent 15A breakers, call an electrician and have two receptacles run from separate breakers, then use two transformers to keep the circuits separate. But it will not improve your amplifier one bit.
In Canada, Hot is the smaller of the two slots (black wire), Neutral is the wider one (white wire), and Ground is the D-shaped one (green wire). But please get some qualified help with this part.
If you want to improve your AC supply, get a powerline conditioner/filter box external to your circuitry. Make sure it's UL or CSA approved.
  Reply With Quote
Old 22nd December 2001, 06:25 PM   #22
JoeBob is offline JoeBob  Canada
diyAudio Member
JoeBob's Avatar
Join Date: Nov 2001
Location: Montreal, Canada
Ok, well after your warning, I guess it's not worth the bother, having to get a professional electrician do it, for if it's that dangerous, I'll stay away from it.

As to Jamie F, I'll use a transformer i nthe soft-start circuit, and since my power suply will be in a different box then my amp modules, I'll put the soft-start circuit there, so the magnetic interference shouldn't be a problem...
  Reply With Quote
Old 22nd December 2001, 08:27 PM   #23
Jamie F is offline Jamie F
diyAudio Member
Join Date: Dec 2001
Location: UK

Thanks for the detail on triacs - points noted.


Please find attached below a layout for the soft-start circuit using veroboard. Basically, I have doubled up Rodís circuit, and used a different RC combination to get switch-on timing correct.

When you switch on the 12V, after about 1 second RL1B switches mains to the load resistors, at which point your power supply caps will start to charge (my rails come up to 32V in about 3 seconds). RL1A switches on about 5 seconds after RL1B, shorting the resistors. They both switch off rapidly when 12V is removed.

The component designators (R1, C1, etc) tally with those in Rodís figure 2. The A parts relate to the resistor bypass relay, and the B parts to the mains switch relay. Make sure you get the diodes and electrolytics the right way round.

Components are as follows:

R1A: 133k
R1B: 220k
R2A, R2B: 22k
R3: 2k2
LK1: wire link
D5A, D5B, D6A, D6B: 1N4004
Q1A, Q1B: BC558B
Q2A, Q2B: MTP3055V
C2A: 100uF 25V electrolytic cap
C2B: 10uF 25V electrolytic cap
RL1A, RL1B: 12Vdc relay (see below)
Veroboard or equivalent
Load resistors: 2x 100R 150W aluminum cased wirewound in parallel (see below)

The mechanical mains switch is not necessary, but is an additional safety precaution. You'd normally leave this switched on.

The relay must have sufficient contact current rating, and if you use a different one, check the coil resistance, as this may require a modification if much different to the relay Iíve used (220R).

My relays: Finder 45.61, contacts 250V 16A, SPNO, coil 12Vdc 220R, spade terminals / PCB mount, US$3.50 each.

My load resistors: Arcol HS150, 100R, 150W heatsunk / 55W no heatsink, US$10 each.

Make sure all mains wiring is secure mechanically prior to soldering, don't use too much solder, and insulate everything well.

Hope this helps.
Attached Images
File Type: jpg soft start board.jpg (48.8 KB, 297 views)
  Reply With Quote
Old 22nd December 2001, 08:49 PM   #24
JoeBob is offline JoeBob  Canada
diyAudio Member
JoeBob's Avatar
Join Date: Nov 2001
Location: Montreal, Canada
Indeed it does help, thanks. I think I understand enough to start for now, if I need any help along the way I'll be sure to post.

Thanks again for all the help...
  Reply With Quote
Old 22nd December 2001, 11:53 PM   #25
AudioFreak is offline AudioFreak  Australia
Warp Engineer
On Holiday
AudioFreak's Avatar
Join Date: Oct 2001
Location: Queensland, Australia
Questions for my LM3386 based power-amp.
Thanks PaulB,

I'll remember that ... In Australia where i live you can usually do such a thing without too much risk of blowing things up....

I also realise my earlier post was in error now

What I should have written was run 2 wall sockets to that case then inside the box connect the ground terminals then feed each transformer from a seperate Hot and Neutral line.

Though over in America and Canada i dont know if this is a safe practice either.
  Reply With Quote


Questions for my LM3386 based power-amp.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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
op amp based power amp kinser Solid State 19 19th November 2010 03:34 AM
LM3886 based amp- questions Atilla Chip Amps 12 6th August 2008 04:55 AM
LM3386 battery powered? Freedom666 Chip Amps 10 14th May 2008 10:12 AM
Opamp based power amp lumanauw Solid State 14 8th October 2007 05:46 PM
Need Help ... Briangt Kit LM3386 doesn't work skappy Chip Amps 16 5th December 2005 10:28 AM

New To Site? Need Help?

All times are GMT. The time now is 09:12 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio