Resistors for 6v down to 5v

[Sir_Lawrence]

Exactly what kind of diodes are you talking about so I could find them? And how are they installed from the switch?

 

[Scottbee]

Something as simple as a 1N5400 will do it. It's good for 3A and will give you about .7VDC drop per diode. To get more drop.. just put them in series.

You can get general purpose high power diodes at Radio Shack (egads).

Just wire them in between the switch and the atty connector.. or in between the switch and battery. It doesn't matter.

But do keep in mind.. they still won't be as efficient as a switching regulator. Really no better than a linear regulator or a power resistor.

 

[vVegas]

Right, but it's the simplest way.
For a 0.7V drop use a normal diode like 1N5400, for a 0.4V drop you can use a hot-carrier diode (Schottky), for example a SB320 or 1N5822

 

[Sir_Lawrence]

Something as simple as a 1N5400 will do it. It's good for 3A and will give you about .7VDC drop per diode. To get more drop.. just put them in series.

You can get general purpose high power diodes at Radio Shack (egads).

Just wire them in between the switch and the atty connector.. or in between the switch and battery. It doesn't matter.

But do keep in mind.. they still won't be as efficient as a switching regulator. Really no better than a linear regulator or a power resistor.

Thanks, but again, I have no idea what a 1n5400 is or what to look for at Radio Shack.
If I knew exactly what Radio Shack called them, I could look them up and try it. I tried looking up 1n5400 and diodes and high power diodes...ect. Nothing.

 

[vVegas]

***.radioshack.com/search/index.jsp?kw=diodes&f=Taxonomy%2FRSK%2F2032269&categoryId=2032269&kwCatId=2032058&fbc=1&filterName=Category&fbn=Taxonomy%2FDiodes+%26+rectifiers

Imho a bit too expensive, but there you can find some...

 

[Sir_Lawrence]

***.radioshack.com/search/index.jsp?kw=diodes&f=Taxonomy%2FRSK%2F2032269&categoryId=2032269&kwCatId=2032058&fbc=1&filterName=Category&fbn=Taxonomy%2FDiodes+%26+rectifiers

Imho a bit too expensive, but there you can find some...

Still couldn't find a 1n5400 on those page you gave. What could I use on a Silver Bullet, to attach to the negative spring, then to the casing to reduce the volts from (2) rcr123a 3v batteries down to 5v?

 

[vVegas]

For example a 1N4003 will drop to ~ 5,3V.
A 1A type should be strong enough. You can test with one or two diodes but don't forget to place it the right way (if it doesnÄt work, just turn around ;-D )

 

[Scottbee]

For example a 1N4003 will drop to ~ 5,3V.
A 1A type should be strong enough. You can test with one or two diodes but don't forget to place it the right way (if it doesnÄt work, just turn around ;-D )

Woah...... not so sure that a 1A GP diode will survive long in this application! A true 5.3V source on a 510 atty yields about 2.2A.

 

[Sir_Lawrence]

For example a 1N4003 will drop to ~ 5,3V.
A 1A type should be strong enough. You can test with one or two diodes but don't forget to place it the right way (if it doesnÄt work, just turn around ;-D )

Can you use with on the negative end of the battery?

 

[CaSHMeRe]

Why using resistors ??? Use a simple diode to bring the voltage 0,7V down or a combination of a diode and a hot-carrier-diode (for 1V)....

you would have to string diodes together ... already been there and done that. resistor/diode/etc... both pretty much the same thing. Resistor being easier to handle because you can order exactly what you need.

 

[Scottbee]

Can you use with on the negative end of the battery?

Yup... you can use it on either end... just spin it around 180. The white band should be on the end that POINTS toward negative.... (if that makes any sense).....

 

[Sir_Lawrence]

So, if I can use a diode, or a resister to bring down (2) rcr123a batteries (fresh they are 6.67v combined), down to around 5v, and I can use it on the neg battery spring to the housing just by turning it around, that would be easy and great.

Has anyone decided on what model number from Radio Shack would be best to use?
Please post link.

Thank you

 

[WillyB]

Something as simple as a 1N5400 will do it. It's good for 3A and will give you about .7VDC drop per diode. To get more drop.. just put them in series.

You can get general purpose high power diodes at Radio Shack (egads).

Just wire them in between the switch and the atty connector.. or in between the switch and battery. It doesn't matter.

But do keep in mind.. they still won't be as efficient as a switching regulator. Really no better than a linear regulator or a power resistor.

That's often said but in the real world they must be tested. Testing (no load) voltages, the 3A 1N5400's dropped .3 and the other .31. Testing a few 1N400X I got about the same with the highest at a .39 drop. I don't know if the drop will be the same under load.

 

[Scottbee]

That's often said but in the real world they must be tested. Testing (no load) voltages, the 3A 1N5400's dropped .3 and the other .31. Testing a few 1N400X I got about the same with the highest at a .39 drop. I don't know if the drop will be the same under load.

My experience has been the same. No load they don't give you an accurate V drop reading. But under load... they are usually pretty consistent at .7V. My Fluke meter actually has a diode setting that will dump enough current into them to give the true V drop.

 

[WillyB]

My experience has been the same. No load they don't give you an accurate V drop reading. But under load... they are usually pretty consistent at .7V. My Fluke meter actually has a diode setting that will dump enough current into them to give the true V drop.

That's good to know. Saved me the trouble of using 2, and then I'd have been too low. Also thanks for the lesson, I just fired up the diode check on my ancient RS meter and it put the .3V one at .597V. Didn't realize what it was used for.

 

[Sir_Lawrence]

Yup... you can use it on either end... just spin it around 180. The white band should be on the end that POINTS toward negative.... (if that makes any sense).....

So, I can actually use a diode or resister housed in the battery spring as long as just the diode or resister touches the neg of the battery, then to the mod housing? It will reduce the volts just the same?

 

[vVegas]

No, with the diodes you have a nearly constant voltage drop, whatever you connect to the other side.
With the resistors you will limit the current.

With both possibilitys you will get nearly the same wattage at the atty.

Example with a 3Ohm atty:

With diode:
U = 6V - 0,7V = 5,3V
I = U/R = 5,3V / 3Ohm = 1,76 A
P = U*I = 5,3V * 1,76A = 9,36W

With 0.6Ohm resistor:
U = 6V
R = 3Ohm + 0.6Ohm = 3,6Ohm
I = U / I = 6V / 3,6Ohm = 1,66 A
P = U * I = 6V * 1,66A = 10W

Understand it ?