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I've a RP1 (Axiom Air in a box) that I'd like to use to feed an outdoor PA System. The PA System is powered by a single GPO Switch than can turn on/off the circuit all the equipment is plugged into.

The RP1 does not boot when power is restored, and you have to press the little white button. Given the equipment is racked this is a no go.

Is there a way of making the RP1 boot on power restoration? I'm happy to make HW Mods as well.

Thanks
Nathan
Hi Nathan,

I was chatting with Andrew about this and neither he or I could come up with a way to make this work. Do you have the option to just leave the RP1 on when the other gear is shut down?
Use a solenoid with a time delay to depress the button for a second.
The system get used rarely so I'd prefer not to leave it on for what could be months between use. I also was thinking about a mechanical setup like Mojo suggested but in Googling this it seems there are various ways of doing this by shorting some pins that the hat uses and I presume that is what the little white button does.

The other option may be a variation of what Mojo's idea. How about say a Timer Switch that could just short the contacts on the back of the white button for XX Seconds - something like - https://www.jaycar.com.au/12v-3a-timer-module-2-seconds-to-23-minutes/p/AA0364
Yeah...I was thinking of that but it gets tricky because you can easily introduce noise into the circuit. That button switch circuit wasn't intended to have external leads connected to it.
I'm an electronic NooB but would't the it be isolated once the timer relay was back to the open position?
Also I don't know what power source to tap without issues without causing issues as well (would prefer not to tap the actual 230V Mains input) and if it 5 / 12 / ?? Volt DC.
Originally Posted By jmone
I'm an electronic NooB but would't the it be isolated once the timer relay was back to the open position?


Those are wires going from the relay to the board and every wire is an antenna. No idea what those antennas will pick up and how the Air electronics will respond. Also when the relay contacts close, they will bounce. Not sure if the button switch is de-bounced internally. It doesn't need to be if a human finger is pushing it.
Mmmm quick test is the Power Supply board is pushing out 20v DC.

Shorting the contacts on the button works to initiate power up of the Pi.
The local electronics store said they had what I want, a Variable Timer with One Shot mode for the relay.... but it was in "Kit" form and I also need a VREG to drop the voltage down to 12v for the kit. Kit form, Soldering! What am I 12?
https://www.jaycar.com.au/the-flexitimer-kit/p/KA1732

Easy they said. Yeah Right. The instructions make little sense to me so just soldered it all together using the picture instead. Scratched my head on that lack of info for what the jumpers do. What could possible go wrong.

Plugged it in to the RP1's PSU daughter board anyway, and it was working! ...but in Interval mode, with the relay turning on and off every 10 sec or so. Found (I think) the jumper to turn it into one shot mode but I've cooked a resister (both on the Axiom PSU daughter board and the Kit).

Back to the Electronics Shop today for parts and more advice!
Any pictures?
I see this thread as becoming almost comical in how it progresses.
The way I learned about electrical and electronics was by cooking everything I worked on. You are following in my footsteps. Good for you. smile
Don't want to embarrass myself with Pictures (yet) as the only thing that looks worse than my Soldering is my Welding!

It is a fun project while on Holidays. Who knows I may get it working. Worse case is the RP1 goes back on the Shelf so I've nothing to lose.

The good thing is the RP1 case is a full chassis but only has a couple of bits in it so there is plenty of room.... but I need to keep away from AC Daughter Board when the top is off. Don't feel like a 230v heart starter!
The Next Instalment....

I went back to the Electronics Shop and got some other guy who told me while the first guy is the expert, the Rectifier is around the wrong way. Swapped the Rectifier and the burnt resistors. The Project Board is dead. No Idea. All it does now is heat the resistors in the RP1 and the project board

Time to move on. Off to a local home automation shop who sells this nifty little "12-24VDC General Purpose Timer" and it is all assembled.
https://www.sprintintercom.com.au/CT1/#catalog.product.manual
They told me it would do exactly what I want! Yeah no.... Turns out the monitoring of the trigger only starts a few seconds after power up. At this point I already have the circuit live so it just waits for a change that never comes. Sigh... spoke to their tech support and got another old time expert who said, no probs. Add in a simple RC Time Constant (one Resistor and One Capacitor) between Pos and Trigger and as the Cap takes some time to charge up this is where you can get your delay needed for the monitoring of the trigger to start. He was not sure of the values but get some caps in the range of 470-2200uf and some resistors in the range of 10-100K, check out some of the on line calculators and you will be good to go. Nope.... this things triggers at 3v. No combinations of Caps/Resisters I just got would not instantly trip the trigger.

That is it for today. Stay tuned for the next instalment smile
After some more research, the next attempt will be this one http://www.learningaboutelectronics.com/Articles/555-timer-delay-before-turn-off-circuit.php to a relay.
If you pay for my trip to the land down under, I'll make it work for you. smile
What - and miss out on the fun of what this stuff is and how it works?!?!?!

Feeling good about the latest design. Nice, simple and just does exactly what is needed.... I think.

Waiting for the electronics shop to open again
So I got it running just how I wanted it. Basically, using the info above + 1 12 Volt Relay hooked to the power button the RP1 now boots up power up. It's basically as 12v trigger. Couple of notes:
- Using an external 12v power source, just drilled an 8mm hole for the 12v socket at the back.
- Keeps everything isolated from the Axiom circuits. The only thing that is physically connected is a Relay that is on for 5 sec at boot to back of the power button (see pic)
- Used the existing mounting holes in the case to mount the board
- Sprayed my board with PCB lacquer in the hope it will slow down the humidity eating it out
- If I don't plug in the 12v then nothing changes in how the RP1 operates previously

Here is where to solder the relay contacts:
https://jmone.org/nextcloud/index.php/s/cbAzKRaqj7d6T5T/preview

This is what it looks like assembled:
https://jmone.org/nextcloud/index.php/s/yS2pXAWPqtsfBDw/preview

So after almost 2years of doing nothing, the RP1 is now in use!
https://jmone.org/nextcloud/index.php/s/YEA2y8KY2nW9AJp/preview

So - what I learnt was:
- The final version only cost a few $ and hours
- The non working versions cost a lot more $$$ and time (I should of built the working version first time around!) smile
- Soldering is not something I am good at
- Soldering Irons burn
- If you break something you can usually fix it.... and on that note, I burn a resistor in the RP1 on an earlier attempt and the local electronic shop did not have a direct replacement and sold me a "10 Ohm 5 Watt Wire Wound Resistor" but given the size they thought in is a "10 Ohm 2 Watt Resistor". While it the RP1 is working fine, I'd like to replace the 5 Watt Resistor with the correct one.

Ian (or someone), you confirm what this resistor is?
https://jmone.org/nextcloud/index.php/s/MyZMBSjTQZkQpXq/preview

Thanks
Nathan
Ah sweet pictures.
It's all so clear now...
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