24 volt operation of car amps - diyAudio
Go Back   Home > Forums > General Interest > Car Audio

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 11th November 2009, 11:23 AM   #1
diyAudio Member
 
Join Date: Oct 2009
Default 24 volt operation of car amps

hello, this is my first post and have some questions. How can I modify a car amp's power supply so that it can safely operate at 24 volt vehicles? Usually, the p.s. mosfets are irfz44 and switch ic used based on tl494. Can the mosfets handle the double voltage? thanks to all replies...
  Reply With Quote
Old 11th November 2009, 02:40 PM   #2
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
The mods would depend on the amp. What make/model amp are you using?

The Z44s may hold. They're rated for 55-60v (depending on the datasheet you use). They would see ~2x the input voltage so it would be close to their maximum rating.

The gate drive voltage would have to be limited.

The transformer would almost certainly have to be re-wound. The higher voltage may make it saturate. An alternative may be to increase the operating frequency. The ratio would also likely be too high and would cause excessive rail voltage. Even if the power supply is regulated, the excessive winding ratio (for the 24v input) would likely cause the filter capacitors on the primary side of the supply to overheat when the amp is driven hard.

The primary side capacitors would need to be replaced if they're not rated for 35v or more.
  Reply With Quote
Old 11th November 2009, 03:05 PM   #3
diyAudio Member
 
Join Date: Oct 2009
thanks very much Perry for the details, actually I am thinking of building a 24v-12v voltage regulator based on tl494 instead of modifying the power supply of the car amp. I do repair works on car amps here in the Philippines and our shop also installs these amps on 24 volt operated 'jeepneys' and we just use 24v-12v converter which is just linear designed and of course bulky.
  Reply With Quote
Old 11th November 2009, 03:27 PM   #4
diyAudio Member
 
Join Date: Nov 2005
I'd say a z44 is going to fail. Any little overshoot at all and you're over the edge with that part. I'd start with a 540 or something. I'd also recommend modifying the converter in the amp rather than adding a converter, if you're already looking at building a converter. You'll have to double the turns on the primary and replace the input filter caps. Make sure the converter IC supply section is able to handle 24 volts too. Should be fun, and much higher performance than adding a converter.

Last edited by Andrew Eckhardt; 11th November 2009 at 03:30 PM.
  Reply With Quote
Old 11th November 2009, 03:47 PM   #5
diyAudio Member
 
Join Date: Oct 2009
thanks Andrew for your suggestions, ok I'll be doing some mods first
  Reply With Quote
Old 11th November 2009, 05:20 PM   #6
Eva is offline Eva  Spain
diyAudio Member
 
Eva's Avatar
 
Join Date: Oct 2003
Location: Near the sea
Send a message via MSN to Eva
Some hints:

- 100V MOSFET for the push-pull PSU, adjusting gate resistors and dead time to keep resonant operation
- Double the primary turns with half the amount of magnet wires
- Adjust RC snubbers on primary windings
- A 15V regulator inserted where power for the TL494/SG3535 and other stuff is taken from the main +B rail.
__________________
I use to feel like the small child in The Emperor's New Clothes tale
  Reply With Quote
Old 11th November 2009, 05:57 PM   #7
diyAudio Member
 
Join Date: Nov 2005
Yeah the 494 can handle up to 41 volts but the driver stage should probably be held to something under 15V for low power FET on resistance but not too high gate charge. You'd probably want a good schematic of the existing circuit to start.
  Reply With Quote
Old 11th November 2009, 10:29 PM   #8
diyAudio Member
 
Join Date: Oct 2009
thanks Eva for the tips I think a 7812 regulator would fit in for the switch IC
  Reply With Quote
Old 12th November 2009, 01:13 PM   #9
Eva is offline Eva  Spain
diyAudio Member
 
Eva's Avatar
 
Join Date: Oct 2003
Location: Near the sea
Send a message via MSN to Eva
The gates of the MOSFET can handle 20V and the control IC and gate buffers (if any) usually drop 1V to 2V, so 15V is better (to get 13-14V at the gates, the most usual voltage in anything but car amps).

Remember to replace capacitors with not enough voltage rating. The input electrolytics should be 35V. 24V systems can produce up to 30V when the alternator is working.

Check this heavy duty 100V MOSFET:
http://www.irf.com/product-info/data...fb4310zpbf.pdf
__________________
I use to feel like the small child in The Emperor's New Clothes tale
  Reply With Quote
Old 5th August 2014, 09:48 AM   #10
Formas is offline Formas  Jamaica
diyAudio Member
 
Join Date: May 2008
Is there any simple schematic for making or modifying the mentioned 24volts PWM circuit available?
Im interested in modifying an amp, simple class ab amp for starters.
  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
CFB and A2 operation hemgjord Tubes / Valves 2 9th September 2008 10:42 PM
Switching 230 Volt Transformer to 120 Volt OMNIFEX Parts 10 6th April 2008 04:34 PM
Inverting operation of Aleph Amps pozo1992 Pass Labs 3 14th March 2008 07:32 PM
12 volt power supply for tube amps caraudionut Tubes / Valves 9 27th April 2007 03:04 PM
operation below fs zenmasterbrian Subwoofers 60 21st October 2006 11:40 PM


New To Site? Need Help?

All times are GMT. The time now is 03:15 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