Will a 5V wallwart work?

[brandonj]

I have access to a plethora of 5V/1A wallwarts, and was hoping I would be able to use them with the wireless transmitter, and standalone receiver. 

My limited knowledge tells me that it should work, but I wanted to check with the experts here, just in case. 

Any thoughts on why it will work or why it won't work are welcome.

-Brandon

[RJ]

If it is regulated it will not. Regulated means it puts out 5 volts no matter what the load until it hits the max load.

If it is unregulated it might.

Why?

 Unregulated power supplys are rated on their voltage at max current. When you plug them in unloaded (nothing hooked to them) you might put a volt meter on a 5 volt and find it putting out 18 volts.

But as you start to draw power from it the voltage starts to fall. On these when you hit 1 amp we know they will be 5 volts. So with only 120 ma from the transmitter what will the voltage be?

I can not say if it will work, but if it is less than 9.5 volts and more than 7.25 volts and not noisy when powering the TX then you are good. you can plug it in and put your meter on the setup and see or let it run while watching the 5 volt 78s05 regulator to see how hot it gets. if you can not touch it for more the 2 seconds after 15 minutes it is too hot so it will not work. It is making the regulator get rid of too much voltage and heating it up.  I like to keep the regulators under 140 deg F if possible.

RJ

[brandonj]

If it is regulated it will not.

I just stuck a meter on one, and it sits constant at 5.2v, so I guess I can assume it is regulated.
That is unfortunate.  I have hundreds of these things

Thank you for the explanation.  I found it very insightful. 

-Brandon

[RJ]

Yes it is regulated and that is too low the built in regulator drop out is 7 volts.

RJ

[lortiz]

RJ,

Since he has 5v supplies, can he eliminate/bypass the 5V regulator and directly plug these into the wireless units?

[brandonj]

That sounds like it should work
But then again, I thought the other way would work too, so who knows. 

I should get my parts for the wireless transmitter on saturday, so i will have to wait to play with it then...

RJ, any reason why that wouldn't work?

-Brandon

[RJ]

Better to have a small amount of patience and do it right. Then weird problems do not come around and ruin your fun.

RJ

[brandonj]

Due to my lack of patience, and curiosity in general, i went ahead and gave it a try - i jumpered pins 1 and 3 on the 5v regulator pads and gave it a go.

So far, it works just fine.   If I have any problems, i'm not going to bother, and just get the recommended power supply. Until then, we shall see what happens.

-Brandon