Calculate how many amps a solenoid needs

[chuck]

you can put it on either of those settings if it's more then 200 ohms your meter will display OL if it's more than 200ohms

There is a better way of doing it, use your meter to read amps then put it in line of the soleniod and power it up and this will give you your amp reading.
Not sure what meter you have got but the black lead stays where it si and move the red lead into the ohter socket (it should say 10a), then connect red lead to the power supply the black lead to postive feed of th soleniod then the ground to ground and turn on power

then you can use your readings to work out total say if they are 55V then lets say if it draws .200 which is 200ma times that by 8 which give 1600ma (1.6A) which means you will only need 1 8amp recicitfer

[The Master]

Ahh. Yes, there is a seperate socket for 10A (no wonder it wasnt working).

Why do you times by 8?

Just to get things straight. When my multimeter is set to 10A does that just mean i cant put more than 10A through it or do i have to times/divide the result by 10? Same for the ohms. If i set it to 200ohms then will 10ohms display as 10 on the display or would it be 2000 or 0.05 or something?

[chuck]

No it will display what ever is been drawn, so no you don't times/divide the reading. so if it draws less than 1 amp the meter will display .200 say or anything over 1 amp it will dispaly 1.5 say. The same goes for the resistance reading only if your set to 2K the and put say 200ohm on there is will read 0.200 and if to put 1K on the it should read 0.999 tp 1.100K

I only times it by 8 to show you, All you need to do is times the reading by the number of solenoids you are running, so if you got 4 then times it by 4, It would pay for you to allow and extra .5 to 1Amp say for all the stuff you will have runnig of the rectifier

[The Master]

Thanx. That really clears a few things up. My new multimeter is pretty confusing at first glance and i was never shown how to use one properly in school :@

I just wondered where 8 came from. Im not sure about the total amount exactly yet but all that has to be arranged before designing the circuit anyway.

Yes, allowing a little extra is always a good idea. Im going to work it out asif all the solenoids are on at the same time. Realisticly i dont think that could ever happen but if a PIC chip goes wrong somewhere and turns them all on i dont want it to start smoking.

Just one more small question about the settings. When moving from 200ohms to 2K the decimal point moves. Is this just so the smaller numbers can be measured with greater precision?.

I have to remember that its measured in Kohms too. 1 = 1K and not 1ohm

[The Master]

Something else ive just thought of. Since im using an AC PSU and a rectifier i need a capacitor. Most of the solenoids are fine but the flipper solenoids buzz a bit because of DC ripple. In this case (or for any other circuit) how do i know what capacitor to use? Ive been told that 24uf is enough but i dont know where that figure came from. Is there a name for this type of equation?

[chuck]

it just means that you can measure higher values that's all, for your meter
Has for the cap the normal rule of thumb is 1000uF per amp, I think you would find that a 24uF would not last long. or it would not remove any ripple out of it at all

[The Master]

Thats what i thought. It seemed a really small value for solenoids. "1000uF per amp" thats easy to remember thanx!