[TriEmbed] Driving 32 5v relays

[dan]

You might also need to check that the chip you're using can supply that
current on each pin. From the datasheet, it looks like the outputs can only
supply 25-35mA each. To get around this limitation, you could use a
transistor and have each pin drive the transistor instead of the relay
directly.

-Sent from my phone
On Jul 16, 2015 11:17 AM, "Adam Haile via TriEmbed" <triembed at triembed.org>
wrote:

> 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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>>
>
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