Newbe - problem with Series Reg Tip 3055 + Z-Diode***HELP** - diyAudio
Go Back   Home > Forums > General Interest > Everything Else

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

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 7th May 2013, 09:28 AM   #1
McLanz is offline McLanz  Germany
diyAudio Member
 
McLanz's Avatar
 
Join Date: Oct 2006
Location: South West
Angry Newbe - problem with Series Reg Tip 3055 + Z-Diode***HELP**

Hi Guys!

OK I'm not a real newbe but lets say I'm not skilled to built regulators with transitors...

I' building a a regulator for my boss's oldtimer. Its an old Chevy which did use 6V battery supply. Now its rebuilt to a modern 12V system.

Problem the ventilation fan still is a (very special) 6V motor. The fan motor shall stay in the car and so I looked how to regulate the supply down to 6V. The current demands are high: between 3 - 5 A. I can't use a LM317/350 it too much for them. I did not find a PWM module which is cheap enough.

So I chose to built a "Series Regulator" controlled by a Z-Diode. I thought that really simple....



Attached is my schematic. I use a TIP 3055 and Z-Diode 7,4V (500mW).
The Tip is mounted to a heat sink. The diode get a voltage by the 470Ohm resistor.

Input and output side is stabelized by 100F cap.


NOW MY PROBLEM: I expected appr. 7.4V - 0.7V = 6.7V on the motor. (It may drop a bit due to the load etc..)

BUT !! I get 2,7V.


What would you check? What do you expect? Is the TIP 3055 maybe not the right choice or is Base- Emmitter leakage problem present? What I can say is that I have plenty of current available and the input voltage is not dropping down
Attached Images
File Type: jpg Tip3055 + Z-Diode.JPG (72.1 KB, 57 views)
__________________
I love high sensitive Fullrange drivers, currently listen with tube amps, NOS DAC, the good old vinyl. I'm optimizing my mains line situation...Located in South/West of Germany. **Love Arts and of course most of all my Family**
  Reply With Quote
Old 7th May 2013, 09:40 AM   #2
diyAudio Member
 
Join Date: Dec 2012
Location: The Jurassic Coast, England. GB
Send a message via Skype™ to JonSnell Electronic
470R with 6Volts across it equals 12mA. A Tip3055 has an average Hfe of 20. Therefore 20 X 12 equals a mere 240mA current and the fan draws 3Amps!
If you use a darlington pair, there will be enough gain to pass the current you require or you could use a wire wound 50Watt resistor at say 2.7R ish. Don't forget the 12V battery will have up to 14Volts on it when charging!
  Reply With Quote
Old 7th May 2013, 09:49 AM   #3
M Gregg is offline M Gregg  United Kingdom
diyAudio Member
 
M Gregg's Avatar
 
Join Date: Jun 2010
Location: UK
As above..

Darlington Transistor

I know it as super alfa its the same thing..

However..volt drop across device * current..how hot is it going to get?

Just be aware of it..

Regards
M. Gregg
__________________
What is the sound of one hand clapping?
  Reply With Quote
Old 7th May 2013, 09:54 AM   #4
McLanz is offline McLanz  Germany
diyAudio Member
 
McLanz's Avatar
 
Join Date: Oct 2006
Location: South West
Default Understand HFE too low

Hi Harleyjon,

so this means I need a NPN with a much higher HFE...understand.

Then I could max the current through the resistor near 500mW of Z- Diode ( leave some safety margin of course) to reach 5A current ability.


Is this right?
__________________
I love high sensitive Fullrange drivers, currently listen with tube amps, NOS DAC, the good old vinyl. I'm optimizing my mains line situation...Located in South/West of Germany. **Love Arts and of course most of all my Family**
  Reply With Quote
Old 7th May 2013, 09:57 AM   #5
M Gregg is offline M Gregg  United Kingdom
diyAudio Member
 
M Gregg's Avatar
 
Join Date: Jun 2010
Location: UK
Keep the current through the zener as low as possible..

NB you also have no current limit at start up and short/ fault conditions.

Regards
M. Gregg
__________________
What is the sound of one hand clapping?

Last edited by M Gregg; 7th May 2013 at 10:03 AM.
  Reply With Quote
Old 7th May 2013, 10:20 AM   #6
Enzo is online now Enzo  United States
diyAudio Member
 
Join Date: Sep 2004
Location: Lansing, Michigan
It is just a fan, not a precision circuit, it doesn't need regulation. All you need is to drop about 6 volts.

If your fan draws 3 amps at 6v then you need to drop 6v at 3 amps. A 2 ohm power resistor in series? It dissipates 18 watts, so a nice 50 watt resistor ought to be OK.

Mouser: 71-RH50-2.0
$4.67 50 watt
Click the image to open in full size.

100 watt 2 ohms were about $7.

You could play with the numbers if you like, but the fan won't much care. I am sure the fan would have worked on a low battery or on a high charging voltage, it isn't picky.

And if I made a glaring math error, let me know
  Reply With Quote
Old 7th May 2013, 10:24 AM   #7
McLanz is offline McLanz  Germany
diyAudio Member
 
McLanz's Avatar
 
Join Date: Oct 2006
Location: South West
Default Question

Hi M. Gregg,

yes its going to be hot but I've mounted it to big heat sink

OK I keep the current low through the z-diode, but...

The TIP3055 has an HFE of 20 and this would mean I need 250mA through the Gate.... can you confirm? (0.25x20 = 5A)

Is a there a better transistor to use?


(I'm reading your article meanwhile - thx)
__________________
I love high sensitive Fullrange drivers, currently listen with tube amps, NOS DAC, the good old vinyl. I'm optimizing my mains line situation...Located in South/West of Germany. **Love Arts and of course most of all my Family**
  Reply With Quote
Old 7th May 2013, 10:51 AM   #8
McLanz is offline McLanz  Germany
diyAudio Member
 
McLanz's Avatar
 
Join Date: Oct 2006
Location: South West
Default Resistor OK - but I need 3 different stages

Hi Enzo,

the Chevy hasn't got a fan regulator to control the rotation speed. My boss asked to have 3 different strenghts. So that why I thought its easier to use a transistor which can be controlled by a cheap signal rotary switch contacting three different Z-Diodes.

Of course I also thought to use a high Watt resistor before, but I assumed it would be more work to switch the high load...

I have a pic here, pretty big heat sink

(Ignore that one resistor hanging around, I used two free wheel diodes)
Attached Images
File Type: jpg IMG_6542.JPG (146.3 KB, 43 views)
File Type: jpg IMG_6543.JPG (131.3 KB, 43 views)
File Type: jpg IMG_6545.JPG (29.2 KB, 43 views)
__________________
I love high sensitive Fullrange drivers, currently listen with tube amps, NOS DAC, the good old vinyl. I'm optimizing my mains line situation...Located in South/West of Germany. **Love Arts and of course most of all my Family**
  Reply With Quote
Old 7th May 2013, 10:56 AM   #9
FoMoCo is offline FoMoCo  United States
diyAudio Member
 
Join Date: Dec 2012
Quote:
Originally Posted by Enzo View Post
If your fan draws 3 amps at 6v then you need to drop 6v at 3 amps. A 2 ohm power resistor in series? It dissipates 18 watts, so a nice 50 watt resistor ought to be OK.
If this is not a variable speed fan, I second this as a best solution.

The circuit you have is not a good idea for heavy loads. You could use a darlington, or a FET, but the topology just isn't right for more than a 100mA, or so.
__________________
Account Deletion Requested: 1/26/2014
  Reply With Quote
Old 7th May 2013, 11:30 AM   #10
FoMoCo is offline FoMoCo  United States
diyAudio Member
 
Join Date: Dec 2012
Here's a circuit that will do three speeds and an off, using a 4 pole switch. Adjust the zeners to get the voltages you desire. I have NOT tested this. I just drew it on as a back of the envelope type of circuit.
Attached Images
File Type: jpg Sany0005.jpg (55.3 KB, 26 views)
__________________
Account Deletion Requested: 1/26/2014
  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
Soldering iron tip problem, help! audio_tony Construction Tips 22 15th January 2011 04:51 PM
Series of Diode on HT Plate Elektor78 Tubes / Valves 2 9th September 2008 10:55 PM
TIP 35C and TIP 36C Tom7227 Car Audio 4 27th June 2007 12:59 PM
Reg problem /help! duffy Pass Labs 1 17th March 2006 10:54 AM


New To Site? Need Help?

All times are GMT. The time now is 11:44 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