(Note - I temporarily "installed" the timer at the end of the first section of track for this test, so it's a short run. Video from my camera so it's low quality).
12Vdc AC adapter $5.25
2.5MM DC JACK, PANEL $2.20
Circuit protector $0.34
3300uF capacitor $1.60
12V Solenoid $5.50
Diode $1.00 (pack of ten)
N-channel MOSFET $0.55
100k resistor $0.50 (pack of ten)
N.O. momentary switch $1.00
RJ-11 Jack $1.00 (for two - used a coupler from Dollar Tree)
Aluminum angle $10.00 (36 inches)
Clamp for capacitor $0.75
Elbow latch $0.60
Strike plate $2.00 (pack of 5)
Miscellaneous stainless screws/washers/nuts ??
I did go a bit extravagant and used #10 threaded brass inserts into the melamine board track for mounting the timer. These cost $0.75 each or $3.00 for the four of them.
Note the start gate switch for the MicroWizard Timer was integrated into this start gate but is not necessary for the operation. This switch and 50 feet of cable were $10 from Microwizard.
If anybody makes this - be advised that the mounting tab of the MOSFET is common to the drain (or high potential lead). This means you need to insulate the MOSFET from the aluminum bracket (and mounting hardware). Given the duty cycle the tab doesn't need to dissipate much heat, therefore doesn't require a heatsink, so I just wrapped the tab (and a bit of the mounting screw) in electrical tape.
Yes - I am using this on a BestTrack now as well.TimInOhio wrote:So, I just stumbled across this project. I had been considering another version, the schematic for which is a lot more complicated. Has anyone tried this method on a Best track? No reason it shouldn't work there, right? The solenoid doesn't care what kind of release it is pulling.
Ok, Thanks That is what I ordered.*5 J's* wrote:I used the 50V caphabcdb wrote:What voltage is the 3000uF Capacitor? I am assuming the 50v. I am attempting to build something similar to this.
I have already built on manual start gate for a single lane best track and used this solenoid*5 J's* wrote:I thought I had already posted this but couldn't find it. While the solenoid works just fine - this door actuator has a longer throw making it easier to adjust. It was a bit harder to mount however.
It worked well and plan on using it this time.
5 J's, do you have specifics for the MOSFET, so I can check my local Radio Shack? The part you link to is a 55V, 22A, .06 ohm - but Radio Shack doesn't have anything matching those specs.*5 J's* wrote:Below is a circuit for a start gate operated by GPRM via the serial port.
12Vdc will be supplied via a 12Vdc AC adapter (500mA or greater). Most people probably have one kicking around or you could order one such as this 12Vdc AC adapter. Note which size plug it is using. This one is using a 2.5mm, so I would need a 2.5mm female jack such as this 2.5MM DC JACK, PANEL MOUNT.
C1 is a 3300uF capacitor and is used as low-pass filter to clean the 12Vdc power.
S1 is the solenoid. I have two options. This one has a 1/4" pull or this door lock actuator which has a 3/4" pull. NOTE: Solenoid did not have enough power - ordered this one instead
D1 is a diode and is reversed biased in the circuit. It is used to shunt the current developed as the field of the solenoid collapses.
Q1 is an N-channel MOSFET and is used as the switch.
R1 is a 100k resistor and is used to prevent noise for triggering the MOSFET.
D2 is another diode and is used to prevent current flow towards the serial port on the computer.
I have also incorporated a normally open momentary switch (SW1) that can be used to "manually" operate the solenoid.
Operation is as follows: The +12v will be applied to the circuit but will sit on the drain of the Q1 MOSFET. GPRM will send the open start gate command to the gate on the MOSFET via pin 4 of the DB-9 connector. One this voltage is applied to the gate of Q1, Q1 will allow current flow from the drain to the source. This will activate the solenoid, allowing the start gate to open. Once GPRM stops sending voltage to the gate of Q1, Q1 will stop conducting and the solenoid will return and it's collapsing field will be shunted via the D1 diode.
I mocked-up an order from your source, but am looking to see if I can avoid having to pay to ship the parts from CA.
Thanks for any info you can give me.
http://web.archive.org/web/200710291453 ... matic.html" target="_blank
Radio shack part number 276-2072. This is the one I used, but do not mount it to an aluminum box without isolating it from the box. It will trigger the switch or ground out. Not sure which, but it would activate the solenoid when the metal base of the switch touched the box. The box was grounded.