Sequential switch & source selector

Amnesia67

New Member
Hi!

I've been there a few weeks ago with a project of sequential switch for my audio installation. I've finished it today, after 5 month of work :D.

Now, no need to turn on one by one the source, audio processor, active filter, volume controller and the two amplifiers, in a defined order! I usually use a tuner, a cd/usb player and a mix table connected to the computer. Wiring the audio outputs of those devices in parallel doesn't work, so I always had to connect the audio cable to the right device, BEFORE I turn it on...

The new device allows me to turn on the source I want to listen by simple push on a switch or with a universal remote control. :) It then turns on the other devices in the pre-definied order. Idem to shut down: press the illuminated switch or the corresponding key on the remote control and everything turns off in the right order without risk of "crash" or "boom" in the speakers. To select a source while listening to an other, I have to press the corresponding key for 3 seconds, that avoids inopportune operation.
The selected audio input is automatically connected to the common outputs (1x Left, 1x Right XLR)



For the electrical part: there are 8 outlets controlled with 8Amp solid state relays (zero crossing), and two outlets controlled with 16Amp SSR for the amplifiers. All relays are mounted on aluminium radiators.

For the audio part: 4x 2 XLR input (supporting symetrical signals) switched with REED relays and 2 XLR outputs.

After listening, there's an standby mode: the electronic circuits are still supplied, programms are running and ready to receive information from user. Devices can be turned on at any moment. The sequential switch can naturally be completely turned off with the main switch (on the front panel of the main casing)

Both picaxe can be re-programmed without opening the casing, there's a Jack input on the back panel and a DIP switch to select which picaxe I want to work on.:rolleyes:

Some photographs:

The first one is a general view. The second is only a detail: it's a plexiglas blade, enlighten with 3 LEDs and which is placed behind the front panel (see later)
 

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Amnesia67

New Member
Only 2 attached files by post...

On the first photograph, we can see the 2 PCB which select one of the 4 audio input to the common output. One board for the left channel, the other for the right channel. It supports symetrical signals. I used REED relays because they support very low current without degradation.

The second photograph represents the high voltage circuit with its 10 zero crossing solid state relays. 8x 8A and 2x 16A. Of course these are maximum ratings, chosen for more security. I should not exceed 10A at the power inlet of the device (no problem).
 

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Amnesia67

New Member
First: the back panel with its 10 230V outlets, its 4 stereo XLR inlets + 1 stereo outlet, the sub D socket for connecting the external control (switchs and IR receiver. The main casing will be placed near to the floor, that's why all the controls are in a seperate casing that can be put in a accessible place). There's also a socket for the Picaxe download cable, the DIP switch for RAZ or selecting Picaxe, and a 12VDC outlet for any other device (fans...)

Second: the front panel whith the main power switch. The slot has been cut with a water jet (not at home :D), it's only for decoration.
 

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Amnesia67

New Member
Main casing by night....

And the external control. The infrared receiver is on the the left. The front panel is a piece of aluminium (drilled at home), 10mm thickness. The cover is made of aluminium too. I bought the virgin casing.
 

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Amnesia67

New Member
And to finish:

- A side view of the external control. I added wood blades because I like wood... that's all, there's any other use :D

- And a view of the back panel with the Sub D 15 plug connected to the main device. The external control is supplied through this cable, so no need of a special DC adapter.


For information, the complete project has cost between 500 & 600€. (The cutting of the front and back panels of the main casing were free, because I know the firm which made it. Else add approximately 150€)
 

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MPep

Senior Member
Excellent project. Well done. Thanks for sharing.
Would you share diagrams and/or code if requested?
 

Amnesia67

New Member
I draw the PCBs with a french freeware "Tracé de CI", very easy to use but complete and precise.

I printed the offset film (not sure that it's the right word:D) on transparent sheats (always double to be sure the contrast is high enough). Then I put everything like follows:

- a thick newspaper
- the epoxy plate
- the 2 offset films (first, glue them very precisely together with adhesive tape)
- a piece of glas
- a few hammers to increase the contact between glas-film-epoxy

And then insolate with a 750W halogen lamp placed at 30cm from the epoxy (my father was plasterer :p. Insolation complete in 3'30").

And to finish revealer & perchloric acid at 45° in a usual basin (I warmed the revealer up too to shorten the exposure time to light, and rubbed the PCB slowly with glowes).

To cut the epoxy > first precut with a stanley knife to cut in a straight line, then cut with the hacksaw. File off the burr. To obtain clean and straight edges, rub the PCB on sandpaper. (and not the sandpaper on the PCB. Put the paper on a flat surface and hold it tensed between two fingers or clamps)

You can do fine work with not much material. Just take care you work in a clean and dark room.

transparent films + perchloric acid + revealer about 7-8€. 20x30cm epoxy plate, 1 layer, 35µm/1,6mm: less than 10€ ;) (www.gotronic.fr => cheap, exhaustive and VERY rapid, they usually send products about 3 hours after the payment!)
 
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