[TriEmbed] Driving 32 5v relays

[Adam Haile]

Stupid question... why not just use digital LEDs?
https://www.youtube.com/watch?v=_nbuSgYoCSQ
Full disclaimer: I have a tiny business that does LED lighting stuff, but I
am also just a huge fan of digital LED strips since they take away
complications like those with relays and such.

More on your original question... no, no... not a resistor to do 14v -> 5v!
You would be dropping 9v and @ 3A be dissipating 27W!   I have bins full of
buck converters like the one linked below that will do 8-23V input and
output a nice steady 5V. They work great and are very efficient.

http://www.amazon.com/Nextrox%C2%AE-Display-Supply-Converter-Module/dp/B00CBCGAL8/

On Thu, Jul 16, 2015 at 11:10 AM, Richard Prevette via TriEmbed <
triembed at triembed.org> wrote:

> I am making a Christmas light display using 32 relays.  Using arduino and
> four 74HC595n shift registers.
> The relays are SRD-5vDC-SL-C.  Here is the question: I may be
> misunderstanding but the datasheet states each
> relay takes 72ma.  I put  a meter across the power and that seems right.
> At one point all relays will be on at the same time.
> That looks like I need a power source that will supply about 2.3 amps.  32
> x 72 x 1000 = 2.3a (Correct ?)
>
> I have a Dell AC adapter that states output at 14v dc and 3 amps.  All I
> need is a resister to lower 14 to 5 volts and
> I good to go?
>
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