Subject pretty much says it all.

I'm looking for a recommended DC power supply, that can provide 5V (+/- 5%) into a series of connected breadboards with a mix of 74xx series TTL ICs on them (and LEDs, EEPROMs, etc).

Back of the envelope math suggests I'll need to draw up to 4Amps at 5V, however, might be nice to have a bit of headroom.

So far I've been using an old iPhone charger that I cut the USB / lightning connector off of and extracted the red and black wires, but, my project is getting big enough now that I am seeing a lot of drops below 4.75V (the TTL chip minimum), even though total current draw is below the rated current of the supply. TTL chips can accept 4.75V - 5.25V.

Does anyone have any suggestions for something I can buy that does this w/o further problems?

I'm looking for something small, like a phone charger type footprint, not a giant bench supply. The idea is the project will be wall-mounted when all done...

I figured this must be a solved problem, so thought I'd ask here. Apologies if this has been covered (didn't find it), or is just incredibly naive to ask (I'm pretty new to electronics, coming from a CS background).

Thanks in advance!

-Alex

 

You can buy higher power encapsulate power supplies such as those sold for use with laptops then add a switching regulator to drop the voltage down to 5V.

Most likely you can reduce power supply current greatly by using CMOS and lowering the power supply voltlage.

 

Back of the envelope math suggests I'll need to draw up to 4Amps

Are you aware most (all?) breadboards aren't designed to carry high currents?

 

I am seeing plenty of 5 Volt, 5 Amp Power Supplies on Amazon under $10 USD. For general bench use you could likely modify a standard inexpensive ATX Personal Computer power supply giving you 12 Volts, 5 Volts and 3.3 Volts for a reasonable price.

Ron

 

Thanks all! I think that gives me enough to go on for now.

(Yes the comment about high currents in breadboards. This is a ~15 breadboard project and I'm going to distribute the power via a star topology or similar, so, other than the initial power rail it comes into, nothing will see currents very high at all (and, TBH, the 4 Amp number is a loose upper bound, just want the power-supply to not be at it's max).

If a single rail up above 2A is a problem (my BBs are rated to 2A), i'll just fork the power input lines before going to any BB elements (I think that works as long as their GNDs are tied).

Thanks all!

 

If a single rail up above 2A is a problem (my BBs are rated to 2A), i'll just fork the power input lines before going to any BB elements (I think that works as long as their GNDs are tied).

Any current on the VCC line needs to return via the GND line. In addition to voltage drops in VCC being problematic, voltage rise due to GND line resistance will also be problematic.

If you want to be less troubled by power supply topology or load on any individual breadboard, you can use a more complicated power distribution model. Use a higher voltage with localized 5V regulators.

In your case, replacing a daisy chained power distribution with a star distribution will likely be sufficient. Just distribute electrolytic filter caps on the boards to prevent localized sag. As I mentioned in your other thread, current draw depends on logic state and which gates are toggling.