How to decrease the voltage? - 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 19th December 2006, 04:48 PM   #1
sunny is offline sunny  India
diyAudio Member
 
Join Date: Oct 2004
Send a message via Yahoo to sunny
Default How to decrease the voltage?

Hi Friends,
I have Yamaha PSR-3000 electronic keyboard and it needs 16 volts switching power supply and i dont have company adapter and at present i have another switching power supply adapter of 19 volts DC of 3.42 Amperes and my keyboard requires 16 volts DC,2.4 Amperes.
So what resistor i should i use in series to get 16 volts,2.4A from 19 volts,3.42 power supply?Your help is highly appreciated and please give the resistor value and its wattage.

Thanks,
SUNNY.
  Reply With Quote
Old 19th December 2006, 07:21 PM   #2
diyAudio Member
 
I_Forgot's Avatar
 
Join Date: Jan 2005
Location: Phoenix, Az.
Inserting a resistor in series with the supply isn't a good way to do the job. If you were going to power a light bulb you could use that technique, but you risk destroying the keyboard because it doesn't draw a constant 2.4 A from it's 16V supply.

Switchers (and all other voltage regulators) constantly compare the output voltage to a stable reference. If you tweak the reference voltage you can set the output to 16V. That can be done with a resistor or two, but you have to find the reference in the circuit.

I_F
  Reply With Quote
Old 19th December 2006, 09:37 PM   #3
lineup is offline lineup  Sweden
diyAudio Member
 
lineup's Avatar
 
Join Date: Dec 2005
Location: the north
Quote:
Originally posted by I_Forgot

Switchers (and all other voltage regulators) constantly compare the output voltage to a stable reference. If you tweak the reference voltage you can set the output to 16V.

That can be done with a resistor or two, but you have to find the reference in the circuit.
.


Yes.
If you could draw exact circuit with resistor values
at that reference point or PIN of that switch supply
it wouldn't be hard to give directions.
If you posted it.

There are many in forum that are Really Power supplies EXPERTS.
Even when it comes to complicated switching circuits.

But this might not be so easy to do.
Probably not a schematic of that supply to find in internet
and to draw a copy just from looking at PCB, is often difficult.


Hope you can solve to get a good 16 Volt supply.
Otherwise, how can you be happy this Christmas

lineup
__________________
lineup
  Reply With Quote
Old 20th December 2006, 04:05 AM   #4
sunny is offline sunny  India
diyAudio Member
 
Join Date: Oct 2004
Send a message via Yahoo to sunny
Now what should i do to get 16 volts ouput at the keyboard?please give me the solution and now i have to play my keyboard for christmas programmes,please help me.

Thanks,
SUNNY.
  Reply With Quote
Old 20th December 2006, 09:31 AM   #5
diyAudio Member
 
Join Date: Jul 2003
Location: Dona paula, Goa
Default Not a PRO solution...

This is a quick solution
see attachment

TIP 122 should be mounted on a heatsink.
5K6 resistor should be 1 Watt
Connect 1k resistor at the output and measure the output voltage. Confirm it is correct and then connect as needed to the keyboard.

Gajanan phadte
Attached Images
File Type: jpg 19 16v.jpg (23.1 KB, 116 views)
  Reply With Quote
Old 20th December 2006, 09:48 AM   #6
sunny is offline sunny  India
diyAudio Member
 
Join Date: Oct 2004
Send a message via Yahoo to sunny
Hello Gajanan phadte,
Thanks for your circuit,now i'll purchase the components and i will try this circuit for my keyboard and is this 560,100ohms resistors of 1/4 watt?and is 0.1 disc ceramic?
Instead of using this circuit and if i simply connect 3 or 4 BY255 in series,is there any problem?please clarify.

MAY GOD BLESS YOU.

Thanks,
SUNNY.
  Reply With Quote
Old 20th December 2006, 10:35 AM   #7
lineup is offline lineup  Sweden
diyAudio Member
 
lineup's Avatar
 
Join Date: Dec 2005
Location: the north
Quote:
Originally posted by sunny

Instead of using this circuit and if i simply connect 3 or 4 BY255 in series,is there any problem?please clarify.
no, i dont think so.

If you buy a number of Diodes whatever type that can take at least 5 Ampere
than you should be able to see how many diodes you need
to get ~16 Volt.

I have used this way in some cases myself, to get smaller Volt Drop.

I think it will be just fine,
because a circuit like you will use, is not require precise 16.000V.

Think about in car .. stuff you use in Car,
will work well and can take any voltage: within range like 11.5 Volt - 16 Volt.
If what you put in your car, can not take this
then it is not suitable for car battery/car generator use.

==============================================
==============================================


Go for simple but good:, your own solution:
Buy a number of 5-10 Ampere diodes.
Not critical what type, as long as they can take 5A.

Than make some tests:

1) Start by adding 5-6 diodes!
2) If voltage is below 16 Volt, than remove 1 diode
and repeat until you get 16.0 volt, or just a litle bit MORE.
Maybe 16.1 16.2 16.3 Volt.
3) Then I am almost sure this will work forever!



Think will be no problem at all for get gear working
before Christmas 2006.

Have a good time!
lineup
__________________
lineup
  Reply With Quote
Old 20th December 2006, 10:53 AM   #8
diyAudio Member
 
Join Date: Jul 2003
Location: Dona paula, Goa
1/4 Watt for 560 and 100 is OK
0.1 ceramic is ok.

Diode solution
U have to buy 1N5404. 8/9 jn number
U have to drop 3 volts and each diode will drop about 0.4 volts


Gajanan phadte
  Reply With Quote
Old 20th December 2006, 04:12 PM   #9
sunny is offline sunny  India
diyAudio Member
 
Join Date: Oct 2004
Send a message via Yahoo to sunny
Thanks to all for helping me.
MAY THE LORD MAKE YOUR CHRISTMAS ESPECIALLY HAPPY AND BLESSED.

sunny.
  Reply With Quote
Old 26th December 2006, 12:16 PM   #10
sunny is offline sunny  India
diyAudio Member
 
Join Date: Oct 2004
Send a message via Yahoo to sunny
Hello Friends,
I have played my keyboard for the christmas programmes very well using the modified switching power supply.I have connected four 6A4 diodes in series on positive line and i'm getting 16.5 volts at the keyboard.
Now another problem has started,the four 6A4 doides are getting too hot and they are burning my fingers if i touch them,I can't understand why the dodes are getting very hot ?The current rating of diodes are 10A and my keyboard requires only 2.5 A.
Is there any solution to this problem?

Thanks,
SUNNY.
  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
Need help with my ST70, decrease in one channel JayH3 Tubes / Valves 1 17th December 2008 04:26 AM
How to decrease this voltage? sunny Power Supplies 8 31st December 2006 11:33 PM
Rail Voltage to Capacitor Voltage Mermprin Parts 6 20th September 2004 04:56 PM
Questions about how to decrease the PASS A-40 amplifier into a class AB amplifier. novtango Pass Labs 2 21st October 2002 02:50 AM
Rail voltage compared to transformer voltage SteveG Solid State 4 23rd July 2002 12:50 AM


New To Site? Need Help?

All times are GMT. The time now is 06:25 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