OSPi to sequence power relays for sound system.

[declanslater]

Since the snow season is here, and the sprinkler season is -not-… I’d like to ask about a different possibility for OSPi.

Since I install and design professional live sound reinforcement systems for a living, my sugguested application would be; A sound system power sequencer.

The problem; when a larger sound system turns on, many times there is a need to delay turning on the amplifiers or other equipment in a system. This is usually due to either a large inrush of current from multiple amplifiers, that when all turned on at the same time, can trip breakers. Another reason to delay turning on certain things is to avoid “thumps” or “pops” that can be produced by different pieces of equipment as they turn on, which would be heard through the amps (if they were on), and contribute to possible damage to the connected speakers (and also nerves of the users). Shutting down the system also can be a problem, where many amps take time to drain the caps inside – they will continue to run for up to several seconds after the amp has been switched off. When other equipment is connected to the input of those amps, and is also switched off at the same time, it sometimes will produce the same very loud “thump” or even louder yet. Many systems are availible (from Furman and Surgex to name just a couple), and they all are fairly expensive. Many lack a web interface, logging, and automation at certain times of the day (say to make sure the system was turned on in the morning and/or off each night), and all require extra wiring to trigger remote relays for distant amps or powered speakers (speakers with built in amps).

I think that the OPSi board would interface perfectly with RIB Relays (common, easy to get ahold of and wire, coil voltage is 24vdc, more of a modular replacement) – http://ribrelays.com/Products/Power-Relays/RIB2401B.html

Since the OSPi board can drive 8 relays (and is expandable) – it’s an excellent fit for this use. Concurrent sequenced relay operation with adjustable delay times for on and off could be easily programmed in a web browser.

I was looking at this page and it includes mention of “SSH passwordless logins”, and remotely running bash scripts on another Raspberry Pi. Something like that could be used to sequence on/off relays connected to other wired or wireless remote Raspberry Pi’s, correct? It might even be possible to add current (power draw) monitoring also.

http://tech.iprock.com/?p=10030

http://shop.openenergymonitor.com/

Hey Ray, You wanna sell more boards right? What do you guys think? A good “winter” project?

[Ray]

Heh, that’s a novel idea. I’ve thought about and heard suggestions on using OpenSprinkler/OSPi/OSBo for various other projects, such as Christmas light controller. But never thought about using it for sound system. I assume the sound system you are referring to runs on power line voltage. To reduce the complexity of wiring, I would actually suggest using RF remote power sockets instead of hard wiring. You can use OpenSprinkler coupled with an RF transmitter to wirelessly switch on/off power sockets. I’ve used this approach in several projects:
http://rayshobby.net/?p=3381
http://rayshobby.net/?p=7817
The nice thing is that a single RF transmitter can talk to several power sockets, so it’s pretty convenient.

[Author]

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