Calculate how many amps a solenoid needs

[The Master]

Hi. I need to make a circuit to control some solenoids. What i would like to know is how to calculate how many amps each solenoid needs so i can get the components to match.

I know the Voltage, wire thickness and number of turns on each coil. Do i need to know anything else and is there some kind of formula for working it out?

[chuck]

you can use ohms law

What is the voltage and the resistance of the coil you then can work out the current draw

The soleniods that we use have 3 wires one is ground, the other is holding voltage and th last one is the pull in voltage, So you put power to the pull in (this pulls the soleniod in) and then the holding volatge takes over, then the power is removed from the pull in. The ones we use can draw up to 30amps only if hold the holding voltage is powered up first.

What type of solenois are the ones you are using ?

[The Master]

The solenoids are for a pinball machine. I looked up ohms law on the internet because i havnt used it since school. I think i worked everything out correctly and it appears that these solenoids are using 0.02 amps each at 55 volts.

Most of them are just 2 terminals but 2 of them (for the flippers) have the firing coil and the holding coil. There shouldnt be more than about 12 solenoids and the rectifier i want to use is rated at 8A. As long as ive calculated it correctly that should be fine. 0.02A does seem a little small for a solenoid though

[T.Jackson]

The solenoids are for a pinball machine.

Repairing or making a pinny?

I used to have some nice pinball machines back in the good'ol days when I actually had a dollar to my name.

High Speed by Williams 1986
Getaway, Williams 1992
Shark, Hankin 1981
Space Station, Williams 1987
Street Fighter II, Gotlieb 1993
Fish Tales, Williams 1992

Plus a couple of other Bally ones, late 70's, so long ago I've forgotten. Space Station was unreal.

Not easy to repair! (Lost a lot of hair)

[T.Jackson]

Arguably one of the most mechanically complex pinball machines ever made was "Haunted House", by Gottlieb 1982.

[The Master]

They used to have fish tales at a pub i used to go to. Then they switched to dodge viper which was also a good game.

The most complex one ive seen so far is the star trek one. There are just so many moving parts and about 4 different ways for the ball to go under the table and pop out somewhere else.

Im actually making my own game from scratch. Ive been playing pinball for so many years and always loved electronics so i thought it would be nice to make one. Ive made about 4 rough versions so far so now ive got some really expensive wood for the playfield and just about all the tools i need. I think im just a spot welder and vaccum former away from starting.

Most of the parts were from an old playfield. My local coin-op repair shop had a harley davidson that was beyond repair so they gave me the playfield for nothing with almost all the parts still attached. A few visits to Ebay and pinballheaven later and ive got everything i need.

Im making the circuits myself (thats half the fun) and thats where this thread comes in. Ive been testing my circuit using a 10A rectifier but its one of those that has spade connections. The only one i can find that can fit directly to a PCB is 8A. I need to figure out how much current will be drawn so i know if it will work. If not then i can either use 2 rectifiers or put some kind of limit on how many solenoids can fire at a time.

This might sound like a stupid question but how do you measure resistance with a multimeter? I used to have one that was easy to use but this new one ive got is so confusing. It only has settings like 200ohms, 2K, 200K.