5v Regulator Problems

[poogiecat]

I've now tried 2 different 5v regulators (one from madvapes and one from Radio Shack) both times my voltage shows 7.5 without the regulator attached and is reading 6.95 with the regulator attached. FYI, I'm using 2 rcr123 batteries. I can't figure out why it's not stepping it down to 5v.

Anyone have any ideas??

 

[cybervex]

Are you sure that you are not wiring the positives backwards?

 

[poogiecat]

Are you sure that you are not wiring the positives backwards?

I initially thought that, so I actually tried soldering it the other way. One way showed me full voltage and the other stepped it down to 6.9.

 

[Keegan1014]

I woiuld do a load test before you go to far.

 

[Keegan1014]

think of it like this get a high voltage atty and your good
LOL

 

[poogiecat]

think of it like this get a high voltage atty and your good
LOL

True! I've got one of those already.

 

[Trebor]

Tell me what regulator (for example 7805, etc) you are using and I'll try to help you.

 

[poogiecat]

Tell me what regulator (for example 7805, etc) you are using and I'll try to help you.

From madvapes.com: MadVapes LLC

From radioshack.com: +5V Fixed-Voltage Regulator 7805 - RadioShack.com

Thank you!

 

[WillyB]

Well I would forget about the RS 7805. Not suited for your task.

This high-power regulator has capabilites up to +5V at 1A

There is also this comment at RS:

I let my friend use it to charge his PSP on a trip but he hooked it up backwards and fried the 7805. I have to take off one star because these things die if connected backwards.

 

[poogiecat]

Well I would forget about the RS 7805. Not suited for your task.

There is also this comment at RS:

I let my friend use it to charge his PSP on a trip but he hooked it up backwards and fried the 7805. I have to take off one star because these things die if connected backwards.

Thanks! Any idea on the madvapes one? I couldn't really understand the spec sheet http://www.fairchildsemi.com/ds/FD/FDU8778.pdf. So I tried it numerous ways as well ... I hope I didn't fry it. But I am getting a voltage reading from it so it doesn't seem that I did.

 

[Trebor]

The Radio Shack is a +5v regulator and its what you should be using for your mod. If you had it in front of you as shown below connect the 7v to the pin on the extreme right of the pic and the 5v output is on the extreme left and the ground(that goes to the negative end of your battery) and you will be in business. The center pin is ground. Good luck

 

[poogiecat]

The Radio Shack is a +5v regulator and its what you should be using for your mod. If you had it in front of you as shown below connect the 7v to the pin on the extreme right of the pic and the 5v output is on the extreme left and the ground(that goes to the negative end of your battery) and you will be in business. The center pin is ground. Good luck

Thanks. Unfortunately that is exactly how I have it wired right now with the Radio Shack regulator ... and it's showing 6.9v. I wonder if I could have blown it out by hooking it up the wrong way initially?

 

[Trebor]

Yes I'm afraid that is what happened. If you have a meter check the resistance from the input and output pins. Should be open or very high(>100K) resistance.

 

[poogiecat]

Yes I'm afraid that is what happened. If you have a meter check the resistance from the input and output pins. Should be open or very high(>100K) resistance.

Thanks ... I guess it's back to the drawing board!

 

[hoogie76]

So first problem.. It'd probably help if the ...... vendor(me) didn't post the wrong spec sheet link , sorry.. The correct spec sheet is:

http://www.ame.com.tw/English/Datasheet/ame8815.pdf top left part (AME8815AEGTxxx)

second problem is that the 7805 regs are not LDO and require around 8 volts to be able to regulate down to 5. The LDO's only require about 5.4 volts to continue producing 5 volts. The AME one has the same pinout as the 7805.

My apologies again for the wrong spec sheet.

hoog

 

[Keegan1014]

i just made a 5 volt box mod.
the regulator was from madvapes and it works perfectly
I gotta give props tp those guys

 

[poogiecat]

So first problem.. It'd probably help if the ...... vendor(me) didn't post the wrong spec sheet link , sorry.. The correct spec sheet is:

http://www.ame.com.tw/English/Datasheet/ame8815.pdf top left part (AME8815AEGTxxx)

second problem is that the 7805 regs are not LDO and require around 8 volts to be able to regulate down to 5. The LDO's only require about 5.4 volts to continue producing 5 volts. The AME one has the same pinout as the 7805.

My apologies again for the wrong spec sheet.

hoog

Thanks Hoog. That spec sheet is a lot easier to understand as well!

 

[Kre8t0r]

So first problem.. It'd probably help if the ...... vendor(me) didn't post the wrong spec sheet link , sorry.. The correct spec sheet is:

top left part (AME8815AEGTxxx)

second problem is that the 7805 regs are not LDO and require around 8 volts to be able to regulate down to 5. The LDO's only require about 5.4 volts to continue producing 5 volts. The AME one has the same pinout as the 7805.

My apologies again for the wrong spec sheet.

hoog

Well that helps alot!! I fried 3 of these tying to figure what went where... 8-o

 

[hoogie76]

Well that helps alot!! I fried 3 of these tying to figure what went where... 8-o

doh.. sorry..

 

[Kre8t0r]

They weren't too expensive.... No worries, thanks for posting the right one tho. Just an idea, you may want to add battery sizes to all the batteries so people building mods can have an idea if things will fit. Just a thought.