Reddit reviews SainSmart 16-Channel Relay Module

The way I do it is with an Arduino and a 16-Channel Relay Module.

http://arduino.cc/

http://amzn.com/B0057OC66U

If you want the actual sound to play outside, you can do that with a sound board, speakers, and a cheap power supply.

http://www.adafruit.com/products/2217

Then you program the lights to trigger however you want.

From personal experience:

LEDs? Yes. Absolutely.

Headlights and wipers? Yes, but the motors on the wipers would be interesting.

7 inch touch screen? There's one built for the Pi already.

Buttons? Yep. pygame could be written to handle all of that. I'm sure other languages could be used, that's just what I'm most familiar with.

10-15 relays? Yep. I personally use a 16-port mechanical switch for a project here at home. You can narrow that down to just a few pins if you know how to program an i2c.

5-10 analogues? Probably. Not sure how many GPIO are left over after using 16 for a relay.

Phone connecting via bluetooth? Not my area, dunno. I suspect so.

Will the Pi handle all of that simultaneously? Heh... easily. The stuff you're talking about is very very simple. It's a lot going on, but the processing power it requires would be hardly nothing at all.

I still would absolutely recommend against it. At least put the headlights on the 'on' position on the relay so if the pi dies, the headlights are auto-on. Take the wipers off of the Pi. That going bad in a rainstorm or snowstorm could be hell.

Seems like it would be pretty simple - find a cheap/quiet air compressor, run the line through a normally-closed solenoid (found this for 11 bucks), and control the solenoid w/ the arduino. If the solenoid is higher than the 5V the arduino can supply, have the arduino power a relay or a power transistor, I use a 12 channel one of these to power solenoids for dispensing water and it works well. Sounds like y'all already have the code set up to do something similar, but give a shout if you need help with that part too

Arduinos overlap quite a bit of PLC functionality. Instead of 24V, everything will be 3.3V or 5V. A PLC typically scans the ladder for inputs then executes everything "at the same time". In Arduino code, variables update immediately.

You'll probably want to look at Adafruit and Sparkfun for LCDs and buttons, as well as relay boards. Amazon carries some selection, but Adafruit and Sparkfun (for the most part) design and manufacture their own boards, so their support is a lot better. Note that if you use a lot of relays (>4), you'll need an external power supply to switch them all on at the same time since Arduinos can't provide enough current to drive tons of relay coils. The one I linked uses an external 12V supply, but I don't know if it's included.

I'm not clear what you mean by I/O board? If it's just the gpio header on the pi itself, it's 3.3v but at 10mA, maybe 12mA? Enough to drive a signal, but not enough to energize a coil. (If you do have a separate board, you'd have to either lookup the specs for it, or let us know which one so we can figure it out.)

So you'll need something to use that to push a relay. Typically a darlington pair, an optoisolator, or a trip to Amazon.

I'm cheap and lazy, so I regularly use either these, which are 3v modules, or these which are awesome, but do need 5v drivers (I usually use an MCP23018 between the pi & the relay board - you'll find a shedload of documentation for this on the googles, but I'll shout-out adafruit's docs specifically). For the sainsmart ones, when they say 12V, they mean you'll need a separate 12V supply to push the relays themselves, they're not expecting 12V from the pi.

These will get the pi to drive n/c & n/o dry contacts you're used to, but I note you also asked about triggers - relay boards won't help protect inputs, so be warned that the inputs are also 3.3v and have very little tolerance (5v will kill them, let alone 24V. Anything you put in the IO lines goes straight into the CPU, so be gentle).


A couple of projects you might want to look into if you want to let someone else worry about the interfaces;

• Kunbus Revolution - not cheap, but Germans doing things the german way, to proper grownup specifications
  
• UniPi - looks more expensive, but works out well when you figure out how many Kunbus modules you'd need to get that many IO (if you just get the board that is. Their housings add grownup prices quickly)
  
• Pimoroni automation hat - Isn't trying to be industrial, isn't trying to charge industrial prices. When they say 'SRS BSNS' they mean 24v, not IEC61131. I went this direction in the end, because I'm cheap.
  
  

https://www.amazon.com/gp/product/B0057OC66U/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

The hoist shares the ground and one of legs that powers the motor also powers the arduino. Ill try and sketch up a circuit quick. The relays I am using are [these] (https://www.amazon.com/gp/product/B0057OC66U/ref=oh_aui_search_detailpage?ie=UTF8&psc=1) which as far as I can tell have diodes and are optically isolated.

SSRs aren't hard to wire up and are a lot cheaper. I bought 20 of them on ebay for ~$20. If it's 12 V relays work well too. Amazon has a card that can control 16 relays for $40.

I can lend you 2 of these:
https://www.amazon.com/SainSmart-101-70-103-16-Channel-Relay-Module/dp/B0057OC66U/ref=sr_1_6?ie=UTF8&qid=1501860037&sr=8-6&keywords=sainsmart+relay

The board I bought is a 12v (since the solenoids are 12v), here's a link to it: SainSmart 16-Channel Relay Module https://www.amazon.com/dp/B0057OC66U/ref=cm_sw_r_awd_FCvSub144A8GM

Turns out I need to use AC as the solenoid driving power, that rules out MOSFETs. I got 2 of these boards to control the turnouts with.

Yeah, I have ordered the resistors and breadboard, and will not repeat the 3v to 5v "solution" again.

But I'm curious where the failure is, exactly. Inside one of the components?


There's no documentation with the SainSmart 16 relay board, so I don't know if there are snubbers on the coils, but I'd be surprised if there were.


The opto-isolators are in place, so I wouldn't think the logic circuitry would be jeopardized by surges from deactivated coils.

Here's the relays I used. The reviews have some good documentation on current requirements and such. I ran 12V to the Vin of the relay boards, as well as to the common terminal of all 32 relays (since the goal was to supply 12V to an ematch when the cue was triggered). The positive end of the cue terminals were connected to the NO terminals of the relays. This means that normally, the ematches are disconnected. When a relay is triggered (by setting an Arduino pin to ground, thus triggering one of the active low relays on the board), the match on that relay is connected to the 12V source. Since the negative terminals on the channels are already grounded, boom.

E-match will detonate with around .5A of current, though most people recommend 1A per match to be sure. This is how we determine how many matches can be fired from one cue; we divide our 12V source by the resistance of all of our matches in series (typically around 2 ohms each) and ensure we can still supply 1A of current. Once the matches detonate, the circuit is broken. Does that clarify things?

Alrighty, so my currents parts list is looking like so:

• 12v Relay
  
• Some type of 12v Power Supply (probably wired, converter from wall outlet)
  
• obviously the raspberry pi itself (+ sd card, power supply)
  
• this 12v solenoid
  
  Where would I buy a flyback diode? What else should I add to this list?