Solenoid Specifications

 I will be using the ball ramp to compare three different solenoids performance. I thought I would list the physical specifications.  They are all rated at 6V, but I have driven then up to 37V for up to 100mSeconds.  They really only need a 15-25mSeconds power pulse. You will need a  10-16A power supply or large capacitor to drive them at that voltage. They are being ranked here by physical size.

 

• Solenoid 1:

A 4 mounting hole solenoid purchased in 2021 from: https://www.aliexpress.com/item/32778544762.html

Weight: 44.1gm

Coil resistance: ~2.3 ohms

Plunger weight: 9.55gm

Plunger movement: 10.6mm

Dimensions: 19.2mm x 60mm x 18.45mm

Performance: https://robotsgo.blogspot.com/2021/06/solenoid-no-1-testing.html

Notes: this is the strongest of the three solenoids. The 4 mounting holes are not symmetrical.  I ended up 3D printing my own mounting block for it!

• Solenoid 2:

 

A 2 mounting hole solenoid purchased 2021 from:  https://www.aliexpress.com/item/32777233179.html

Weight: 30.86gm

Coil resistance: 3.82 ohms

Plunger weight: 7.61gm

Plunger movement: 11.3mm

Dimensions: 15.5mm x 58mm x 13.9mm

Performance data:  https://robotsgo.blogspot.com/2021/06/solenoid-testing.html

Notes: mounting holes are M3 and are 15mm apart.

• Solenoid 3:

 

A 2 mounting hole solenoid purchased from: https://core-electronics.com.au/mini-push-pull-solenoid-5v.html

Weight: 12.4gm

Coil resistance: 3.4 ohms

Plunger weight: 1.95gm approx

Plunger movement: 3mm

Dimensions: 12mm x 29mm x 11.3mm

Performance: https://robotsgo.blogspot.com/2021/06/solenoid-no-3-testing.html

Notes: mounting holes are about 10mm diagonally apart and about 1.3mm diameter and have no thread. The plunger can not be removed. This does come with a handy JST-PH 2pin connector on the end of the wires.

While I tested each of these using a 45.6gm golf ball, it would be idea to have the striking plunger to weigh the same weight so that all the kinetic energy is imparted into the golf ball.  As it is, the whole ramp moves backwards when the plunger hits the ball.  I did test a ping pong ball on the ramp with solenoid #2 and at full strength, it lunched it into the end of the ramp and into the air.

Our little mini solenoid will be striking a ping-pong ball that weighs around 2.7g, so very close to the ideal weight.  As we are trying to play Robo soccer, we don't want the ball moving too fast.