Skip to main content

Power Supply

After finally figuring out those shift registers, my concerns turned towards my power supply needs.  Logic circuits work on either 3.3V or 5V so a PC PSU would be perfect.  On top of that, they are a dime a dozen.   Someone should have a spare one lying around.

Formally Functioning PC PSUs

Well, someone did have some lying around.  The permanent marker demarkation on the left one says it all.  At least they are useful for parts.  Not satisfied with the quality of my previous procurement, I set out to purchase the cheapest power supply I could find.  I purchased a Coolmax 500W power supply from Canada Computers, who happens to be a fantastic retailer for anything computer related.  I don't really buy from anywhere else anymore.

 My control circuit power supply needs are now furfilled.  Unfourtunately, the 12V rails of the PSU do not have enough voltage to actuate the solenoids that are used in 90% of the mechanisms in a pinball machine.  I discovered this after purchasing two brand new flipper mechanisms from http://www.actionpinball.com.  They came at the highway robbers discount price of $35 each along with the solenoids costing $13 each.  However, I justified this purchase in that the flippers were the main mechanism in the game and I wanted to maintain the 'feel' of a real pinball machine.  

Two Flipper Mechanisms

When I hooked up the flipper coil to the 12V for the first time all it could manage was too prevent the core from being pulled out by the spring. Turns out I had it hooked up wrong. You can see the 3 terminals on the flipper coil in the picture. There are 3 because there are 2 coils inside. The reason there are two coils is because the large one generates a lot of heat and having it powered for a long time would burn it out. This would be such a case when the flipper is held in the up position. So the flipper mechanism opens a leaf switch so that it only powers the secondary coil when open. This is called an EOSS switch, or end of stroke switch. Once I hooked it up properly it had more kick but not enough. I then read that the coils would run off of 24V. I tried used the +12V and -12V but the max current was only 1A so the circuit breaker would go in the PSU. The resistance on these coils is only 4.6 Ohm which means on a 24V supply they would pull 5.2A. This makes the PSU unhappy.
Labels:

Comments

  1. Anonymous7 November 2018 at 07:44

    This article is an appealing wealth of informative data that is interesting and well-written. I commend your hard work on this and thank you for this information. You’ve got what it takes to get attention. dell power supply

    ReplyDelete

Post a Comment

Popular posts from this blog

MOSFET Driver Board

Final version?  I hope so.  I have gone back and redesigned my solenoid driver board several times.  In previous versions I attempted to offload some of the logic from the microcontroller.  For example, I used a Schmitt-Trigger [74HC14] with an RC network to provide a single pulse to the solenoid.  Also, I added in a PWM signal to set the average voltage 'seen' by the solenoid.  This worked but was very limiting to have the pulse length hardwired in and it was difficult to adjust without more expensive precision potentiometers. I chose to simplify my circuit to make it a general MOSFET driver for flexibility.  Since I have more than enough space inside my pinball cabinet, it was not a problem to have the extra boards.  The boards were designed to have 4-channels since by default I would get a minimum of 10 boards for the same price from Seedstudio.  Also, the cheapest board option was restricted to 10cm x 10cm otherwise the price balloons quickly. Driving 48V from a separa
3 comments
Read more

Pinball Cabinet Beginnings

I was getting to the point where I really needed to build on something. I have numerous pinball parts but have nothing to attach them to. I managed to find some pinball plans for a Williams Widebody pinball machine. All the measurements are in mm sadly even though all pinball cabinets are in inches. I converted and change it all to the nearest quarter inch. Well sort of. The guy who measured this was intending on using 45 deg cuts in the corners. My skill saw is too cheap for that so I changed the measurements for butted joints. The interior is set for a 23.5" wide playfield. The length of the cabinet is 51.5" in total. I used 3/4 inch plywood so the bottom would be 50" long for example. You can pretty much dimension the rest from there.  I did get a little chipping of the plywood but I went out and bought a blade with more teeth for finer cuts. It's a 60 tooth saw blade and my skill saw doesn't really have enough power for it so I have
Post a Comment
Read more

Pinball Solenoid Control

Pinball solenoids come with designations like 23-800.  The first number, 23 in this case, represents the American Wire Gauge (AWG) used.  The second number, and the more important number, is the number of windings which is related to its power rating.  A solenoid with less windings, say 400, is more power and is used for such applications as actuating the flippers.  These solenoids get very hot very quickly, which increases the resistance of the solenoid thereby decreasing the current and therefore the power.  To avoid overheating, these high powered solenoids will have two coils.  One for the main actuation of the solenoid, and another to maintain the position.  The second solenoid will have a smaller wire gauge and more windings.  In example, my flipper 'coils' are 15-411, 15 AWG and 411 windings.  They are quite strong and found in some of the latter Williams pinball machines such as the popular Adams Family machine.   You can find a lot of good additional information
3 comments
Read more