How to decrease the voltage?

[lineup]

does not need to be any danger
our fingers can not take the heat that semiconductors can

what this indicates, is that keyboard draws High Current
and so the power in diodes is quite a bit.

19-16.5 ~ 2.5 Volt
say 3 Ampere
Power dissipated in diodes= 2.5V x 3A = 7.5 Watt.
-----------

What you can do:

1. place these 4 diodes not to close to eachother
2. place them in free air = not close to any PCB surface
this will allow air to flow and COOL from ALL sides of each diode
3. usually we can let the pin of such HOT devices be a bit longer
so that the body of device is LIFTED like 5 mm ABOVE PCB

Other components like small resistors etc. have there body close to board
to reduce the length of connection pin.
This is generally good.

But for HOT diodes or POWER Resistors (without Aluminum heatsinks)
can be good to keep them a bit up in air.

*************************************************

If you still worry about heat in your diodes,
there are Rectifier Diodes in TO220 package.
Which allows you to screw a little Aluminum metal piece onto diode.


This image shows a TO220 package, with one diode.
Has got 2 pins, instead like a TO220 transistor = 3 pins

****** sidenote:
TR-ansistor
TR-iode
---> the TR comes from TRIO = 3

TRiode - 3 pin diode (a sort of Tube / Valve, which was before all Transistors)


Lineup
Lineup Audio knowledge Bureau
http://lineup.awardspace.com/

[sunny]

What is the number of this 2-pin TO220 rectifier diode?

SUNNY.

[lineup]

Originally posted by sunny
What is the number of this 2-pin TO220 rectifier diode?

SUNNY.

There are many.
Check the website of your Electronics Dealer.
Browse:
Components - Semiconductors - Diodes ....
And look for single diode in TO220 package(capsule)
that is rated something like 5-10 Ampere.

Maybe someone member from your neighbourhood, country
would be so kind give us
a Link to supplier or Part Number of one such suitable Rectifier Diode.

All the big semiconductor manufacturers make such high Current Diodes:
SGS Thomson, Philips and them from Japan, Korea, China, too.
There are plenty of variants for different voltages and currents.

lineup

[sunny]

still i cannot find this 10A rectifier diode.Please suggest me suitable low cost 10Amperes diode.

Thanks,
SUNNY.

[lineup]

Originally posted by sunny
still i cannot find this 10A rectifier diode.Please suggest me suitable low cost 10Amperes diode.

Thanks,
SUNNY.

So what is the website to Big electronics components supplier
in INDIA.

I can go there have a look for you.

Members from India, where are you, this christmas?



lineup - knows there are several other active and good members from India

[lineup]

IRF has got a line of such diodes in TO220 package

The thing is maybe to find a supplier, preferably in India
or not too far from you.
But if you can buy from other countries, like from Online electronic web shops, then is no problem.
Like Singapore, Hong Kong, Japan etc.
If you live near New Dehli you can go buy them in a shop, for sure.

Here are 2 suitable diodes from International Rectifiers www.irf.com
Two TO220 power diodes from - irf.com - International Rectifier

They are called:
10ETS08 ( 10A, 800 Volt ), 10ETS12 (10A, 1200 Volt)
You would only need max 100 Volt, so both of them will do, more than enough!
10ETS08 Datasheet PDF - with details


These diodes will cost you more money, than if you go for normal Axial 2 pin Power diodes.

I think those you have now ( 6A ) will do well
- if you put them in free air for some cooling ( see my prev. post )
but of course you can upgrade to 10A, if you like.


lineup

[sunny]

Can i use 10A1 diode?i think It is a Axial 2 pin Power diode and is this diode costs less than 10ETS08 or 10ETS12?

SUNNY.

[lineup]

Originally posted by sunny
Can i use 10A1 diode?i think It is a Axial 2 pin Power diode and is this diode costs less than 10ETS08 or 10ETS12?

SUNNY.

Yes
this would be perfect - and better price, if you can find a shop.

Generally it is good to have some margin:
Use 3A diodes for 1 ampere currents
Use 6A diodes for 2 ampere
Use 10A diodes for 3-4 ampere

The same goes for Transistors and Resistors.
No components will work at best,
when they have to do HEAVY WORK.
Same goes for people.
A little child can not carry so much weight, in a good way,
as a big mother can.


See my attached Picture, with Image and Details
of 10A1
The manufacturer is called Rectron
datasheet:
http://www.rectron.com/data_sheets/10a05-10a10.pdf

10A1
It is an axial 2-pin power silicon rectifier diode
FEATURES
* Low cost
* Low leakage
* Low forward voltage drop
* High current capability
* High surge current capability
MECHANICAL DATA
* Case: Molded plastic
* Epoxy: Device has UL flammability classification 94V-O
* Lead: MIL-STD-202E method 208C guaranteed
* Mounting position: Any
* Weight: 2.08 grams


lineup

[sunny]

Thanks a lot for helping me.Now my problem has completely solved.

SUNNY.

[lineup]

Originally posted by sunny
Thanks a lot for helping me.Now my problem has completely solved.

SUNNY.

As you can see in Datasheet FIG.2,
FIG. 2 - TYPICAL INSTANTANEOUS FORWARD
CHARACTERISTICS
the 10A1 power diode
has got a voltage drop ( VF = forward voltage )
of something like 0.8V at 3A

so we can think
3 diodes would have a drop of ~2.4V
4 diodes would have a drop of ~3.2V
.... something like that


you are welcome back
if there is anything else you want to discuss or ask
in electronics

as you know, we are many here
that could possibly try to give advice


Regards to sunny, India
from lineup, Europe