(This is a re-post of something I submitted a few weeks ago before the Projects forum disappeared.)
I'm working on a project that needs more amps than I've worked with before. Can you let me know if my assumptions are correct, and even recommend the type of power supply I'll need?
The project: I have a "mechanical" digital clock where all the segments of the digits are controlled by solenoids. There are 34 solenoids - each has an initial draw of 12v @ 1.4amps, and to maintain the pull it takes 12v@450mA. The solenoids are controlled via a Basic Stamp and some other electronics: they're wired in parallel via a set of transistors. Pretty straightforward.
The problem: how big a power supply - and what type - will I need? Currently, my 12v @ 3amp old laptop brick doesn't seem to have enough juice to power all the solenoids - even though they update in "ripple" fashion (a slight delay between each solenoid firing to prevent too much current draw).
I suppose I'll need a power supply around 12v with around 15amps (34 soleniods * 450mA)... but will that be OK (i.e. safe) if only a few of the solenoids are active at any given time? Do I need to be concerned with "switching" or "no load" power supplies? Anything else I should pay attention to?
Any advice gratefully recvd.
I'm working on a project that needs more amps than I've worked with before. Can you let me know if my assumptions are correct, and even recommend the type of power supply I'll need?
The project: I have a "mechanical" digital clock where all the segments of the digits are controlled by solenoids. There are 34 solenoids - each has an initial draw of 12v @ 1.4amps, and to maintain the pull it takes 12v@450mA. The solenoids are controlled via a Basic Stamp and some other electronics: they're wired in parallel via a set of transistors. Pretty straightforward.
The problem: how big a power supply - and what type - will I need? Currently, my 12v @ 3amp old laptop brick doesn't seem to have enough juice to power all the solenoids - even though they update in "ripple" fashion (a slight delay between each solenoid firing to prevent too much current draw).
I suppose I'll need a power supply around 12v with around 15amps (34 soleniods * 450mA)... but will that be OK (i.e. safe) if only a few of the solenoids are active at any given time? Do I need to be concerned with "switching" or "no load" power supplies? Anything else I should pay attention to?
Any advice gratefully recvd.