entropy continued?

This is where we talk about testing, measuring and repairing things. Sometimes we have to repair the equipment we use to test, measure and repair other things. It's an endless cycle of fixing the broken things we need to fix other broken things.
billshurv
Posts: 163
Joined: Thu Feb 01, 2018 7:07 am

Re: entropy continued?

Post by billshurv » Mon Mar 11, 2019 5:49 pm

Progress. Made a new umblical up. Swore at infinity for using the shield for signal carrying and hooked a 9V battery to the standby line. Relay click, standby light goes out. Now can I find my stash of PP3 battery connectors anywhere? Nope. Ah well £2.50 gets me a box with a switch so come thursday will be able to see if this beasty works. Hopefully my second most delayed project will finally get some use. At least if it doesn't go 'fzzt' with a signal.

(Wife is amazed as she never thought I would even get this far. She may be less impressed at true full range music reproduction ! ).

Gold
Posts: 481
Joined: Sat Dec 01, 2007 6:20 pm

Re: entropy continued?

Post by Gold » Sat Mar 16, 2019 2:39 pm

I got the project box and Condor 28VDC power supplies to make the external Sontec power supply. The client wants to use XLR-7 as the connectors as that’s what the GML PSU uses. The GML puts out +/-28VDC and +/-18VDC. The Sontec just takes 28VDC and regulates down to +/-17VDC on the board.

The selection of project boxes available is sorely lacking. I really need to be able to make my own enclosures. This box I got is a terrible design. It’s a standard two piece sheet metal enclosure with two U shaped pieces. If I want the connectors on the short side the box is upside down. It’s 20ga steel and flimsy for the heavy PSUs.

I’m going to mount the PSU’s on two pieces of bar stock which will attach to the ends of the box. This will give the box much more strength.

A friend has scared me from using thermal breakers on the DC side. He said they are slow and inaccurate. The boards draw 100mA. He thought I’d get false tripping if I used a 100mA breaker. I could use a 150mA breaker or use a 100mA slo blow fuse. Using a fuse leaves my options open. The supplies are 1A per leg so there’s is a lot of extra power. With fuses you could change the rating as needed.

I think I’m going to buy a $50 sheet metal brake and a pair of sheet metal shears. I’ll see how far I can get.

brianroth
Posts: 65
Joined: Mon Jun 17, 2013 2:11 pm
Location: Salina, Kansas
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Re: entropy continued?

Post by brianroth » Sat Mar 16, 2019 7:37 pm

I've used Hoffman "screw cover pull boxes" to house various power supplies. They are available in a variety of sizes, with and without conduit knockouts. Sold at many electrical supply houses, and I've seen a small selection at Home Depot. Nice and heavy duty.

https://hoffman.nvent.com/en/na/Product ... ver-Type-1
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Professional audio and video systems design/installation/maintenance.
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Gold
Posts: 481
Joined: Sat Dec 01, 2007 6:20 pm

Re: entropy continued?

Post by Gold » Sun Mar 17, 2019 9:29 am

Those look nice Brian. I’ve never used that type of cable clamp. Do you need a special tool to instal those?

brianroth
Posts: 65
Joined: Mon Jun 17, 2013 2:11 pm
Location: Salina, Kansas
Contact:

Re: entropy continued?

Post by brianroth » Sun Mar 17, 2019 12:03 pm

Those are made by Heyco and sold at Mouser, etc. in a variety of sizes for different wire diameters. I use ignition pliers (which is a useful tool for many applications) to install them.

https://www.sears.com/craftsman-ignitio ... 904513000P

Bri
Professional audio and video systems design/installation/maintenance.
www.BrianRoth.com

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