Power Problems

A project log for Audible notifications by a Grandfather's clock

Eight chimes can sound in different patterns whenever I receive a notification through IFTTT

borazsloborazslo 04/19/2016 at 04:463 Comments

Among the notes of the first version of the circuit I mentioned that still I am using two different power sources. I use a 5V/2A for the RPi3 and another 5V/5A for the solenoid circuit. Unfortunately the circuit consumes all the 5A. So if I connected the whole project to the 5V/5A source, the RPi would not have enough stable power. :(

One solenoid needs 0.6A. So the step-up power converter needs to produce 0.6A (and 20V). For this efficiency the step-up converter consumes full 4.8A from the 5V/5A power adapter. Oh, and the step-up converter overheats fast, even though a solenoid works only for 0.1 sec / hit, so the consumption comes in strikes. (But what if I want to strike different rods in the same time?)

I see two possible solutions with my very limited knowledge:

Can you help me to find a solution, please.


Frédéric Druppel wrote 04/19/2016 at 17:59 point

For the power supply, you could use a power brick from an old laptop (these give you a voltage from 19 to 21 Volts in most of the cases), And instead of a linear voltage regulator, you could use something like the PT5101, which works like a LM7805, but is much more efficient.

Hope it helps !!

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borazslo wrote 04/20/2016 at 01:11 point

Thank you for the help. I can use it. But can you say more about the alternatives of LM7805? I cannot find the PT5101, but I found a cheap OKI-78SR-5/1.5-W36H-C by Murata

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Frédéric Druppel wrote 04/20/2016 at 05:06 point

The PT5101 is a 5V buck converter. I use it sometimes, but it's a little bit tricky to find (a friend of mine gave me a few). Of course, you can use another buck converter (like the one you mentioned) to regulate the voltage. If you were using something like 9-12V, an LM7805 would be enough, but because of the higher voltage, a "more advanced" buck converter would be just perfect, because you don't have to use a gigantic heat sink (but you probably already knew that ;) )

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