Sequenced Mains Switch (DMX Controlled)

Reading this thread has prompted me to float another idea I had about switching my switchmode power supplies on and off remotely.

From my post in that thread:

Anyway, it occurred to me that if I were to make a board to do this, it might as well have more than one relay (maybe room for 4) so it could turn the switchmode power supplies on one at a time. Each one would turn on a few seconds after the previous one. This could stop them all drawing their inrush (surge) current at once and potentially tripping the house circuit breaker.

Multiple relays could also be useful for where multiple power supplies are fed from separate power outlets. One of the power inputs to the board would power the first output and the on-board electronics. The other inputs and outputs would be just relay connections.

Comments?

 

I use "keep alive" in my DR4, so the second option probably wouldn't be good for me.
But I think if it could be done in a "latch" style situation, it would be very useful.. Similar to your RF controller board, something like:
CH1:Relay 1 On
CH2: Relay 1 Off
CH3: Relay 2 On
CH4: Relay 2 Off

You could then setup a startup sequence that sent On commands for all relays (staggered by a second or two each), and similarly a shutdown sequence, and set these up in LSP to run at the start and end of the show...

 

That's a good idea Kane. Once the board is made, we can fiddle with the micro firmware to get the best functionality, or have different firmware for various control methods.

 

was these controllers a once off special from rockby at $15 ?
are they able to provide you with stock if you got lots of orders?
is it only 4ch like on the power outlets or can more be added to make work

 

The $15 Rockby special was for RF controlled switches. That thread is over here.

This idea is for a hard wired solution where RF may not be suitable. (not enough channels or distance issues)

 

The other issue for the RF switches is the inrush current of larger switchmode power supplies.

I had an RF mains switch on both of my power cabinets (2x 240W + 1x 200W PSU in each) and the relays on both have become sticky (staying on).

It's looking like a DMX sensing mains relay will be useful (for me at least) for controlling larger loads.

 

I found a nice 12V coil, heavy duty (30A) contact, PCB mounted relay at a reasonable price. (< $5)

I was thinking that a control board with a single relay (output) would suffice for a lot of situations.

It could also have the drivers for additional relays (on a slave board) for turning on multiple power supplies in a controlled manner.

 

David, I like the idea of a 1-2 channel board for switching power to my controllers.


Some ideas:


# power the controller from 12V, and provide 5V for a local DR4, using one of the 1.5 amp Smps modules.


# a seperate E1.31 /Dmx application to control the relays. I have a habit of restarting vixen during the day/ testing period, so it would good not to have to cycle to power supplies.


The board would have to have a slim form factor to fit inside my CG1000 with my DR4.

 

Another idea - how viable would it be to have some sort of smoke detector input for automatic shutoff? Like using a security alarm detector?

 

Good ideas John. I'll look into that.

Driver, it could have an Emergency Shut-off input I guess.

 

It's a rainy day so I've started the PCB design for this project.

I'm putting 4 heavy duty relays on the board and just bringing the (normally open) contacts out to 2 way terminal blocks. That will give the most flexibility when wiring up.

More detail to come as I progress with the design.

 

PCB design is pretty much done. Some stats:

• 240Vac input (terminal block)
• On-board transformer to power electronics and relay coils
• 4 x H/D relays, each with N/O contact (terminal blocks)
• DMX in / thru on RJ45 connectors (ESTA standard pinout)
• DMX termination jumper
• 5V, Mode & DMX LEDs
• PGM button for setting DMX address
• Trigger input for some future function
• 2 x option jumpers (purpose to be determined)
• ICSP header to reprogram PIC if required
• Approx 100mm x 125mm (4" x 5") board size
• 3mm hole in each corner of the PCB

The relay outputs are "uncommitted" normally open contacts. They are meant to switch the active wire of the load.

 

Looks good but I do have a few comments.


If you've already though about any of these then just ignore.


Since most of the sequencing programs will turn off everything at the end of a song wouldn't that turn off the power? Maybe you'd should require a sequence of values sent so that a simple change from 0 - 255 - 0 wouldn't turn the relay off-on-off. Maybe something like 0-64-128-255-0 turn on then 0-255-128-64-0 turn off. Anytime it sees 0 it assume a new sequence will be starting on the next non-zero value. This is only and example as I'm sure there are better sequences one could use.


Might I suggest SPDT relays so one could have NO or NC contacts.


P-DMX so the board wouldn't need a local PS for it to function.



As always, IMHO


John

 

I'm not sure exactly how the relays will be triggered yet. It may be that more than one version of the firmware is required. Maybe one that has 1 to 1 mapping of channels to relays, another with 1 ON, 1 OFF, 2 ON, 2 OFF channels and maybe one that just detects a valid DMX stream. These could all be the same firmware with the option jumpers selecting the mode most likely. I understand the coded sequence idea, but sounds like more effort to code than I'm keen on right now - maybe later.

The low cost, heavy duty contact relays I chose only have a N/O contact. I think that 99% of applications would not require a N/C contact.

That's a good idea. I did have that on my mental check list, but forgot it by the time I got around to starting the schematic. Should be easy enough to route the P-DMX power pins to the +12V rail via a jumper.