Folsom's great little 7297 Chip Amp

BRN · « **Reply #480 on:** 15 Aug 2016, 12:55 am »

Mike,

You could use a switch like this one from eBay:

http://m.ebay.com/itm/16mm-12V-Latching-Push-Button-Power-Switch-Aluminum-Metal-Blue-LED-Waterproof-/141700412231?nav=WATCHING_ACTIVE

You would wire the the section rated at 250v 3 amps to the AC before the power transformer and the LED to the aux of the Antipole. You will need to pad the LED with a resistor since the Antipole aux puts out around 24v DC and the LED is only rated for 12v DC.

lacro · « **Reply #481 on:** 15 Aug 2016, 02:07 am »

Quote from: BRN on 15 Aug 2016, 12:55 am

Mike,

You could use a switch like this one from eBay:

http://m.ebay.com/itm/16mm-12V-Latching-Push-Button-Power-Switch-Aluminum-Metal-Blue-LED-Waterproof-/141700412231?nav=WATCHING_ACTIVE

You would wire the the section rated at 250v 3 amps to the AC before the power transformer and the LED to the aux of the Antipole. You will need to pad the LED with a resistor since the Antipole aux puts out around 24v DC and the LED is only rated for 12v DC.

Isn't 3A a little light duty?

Folsom · « **Reply #482 on:** 15 Aug 2016, 02:52 am »

Not for this application. Let's say the amp uses 4.1a full load, times 25v (actually 17.8v). You've got about 100w. 100w/120v = .84A.

limits · « **Reply #483 on:** 15 Aug 2016, 02:37 pm »

Hi KR500--The case I linked earlier from Surplus Sales is tall enough to fit the Hammond 185F16 transformer. It is pretty close, but it fits. I have a thin mat and rubber shoulder washers and washers between the bottom of the enclosure and transformer, and a thin foam pad sandwiched between the top of the transformer and the top cover of the enclosure.

I ended up using the captive power cord and the steel heatsink (for the 7297 chip) that came with the enclosure. I removed everything else.

Good luck with your build!

limits

KR500 · « **Reply #484 on:** 18 Aug 2016, 08:37 pm »

thanks for your feedback on the case limits, I ordered one today.

mlundy57 · « **Reply #485 on:** 18 Aug 2016, 08:47 pm »

Jeremy,

You've said a 10k Ohm resistor is OK for discharging the caps in the power supply.

Is more than 10K better?

Does it matter if it is a 1W, 10W or 12W resistor?

Folsom · « **Reply #486 on:** 18 Aug 2016, 09:02 pm »

1w is fine. Higher just means it's slower. It wont hurt anything.

limits · « **Reply #487 on:** 18 Aug 2016, 09:19 pm »

Hi KR500--Good deal...nothing fancy, but it worked well for me. Best of luck on your build. Despite my (self imposed) issues, I had a lot of fun building it, and am loving how well it has settled in--sounds awesome!

limits

limits · « **Reply #488 on:** 18 Aug 2016, 09:30 pm »

Regarding the transformer, I used the Hammond 185F16 part. I noticed the 185G16 is another quarter inch taller, which would be a deal breaker in my enclosure. I wonder if this was the issue walkern ran into?...

limits

mlundy57 · « **Reply #489 on:** 18 Aug 2016, 09:33 pm »

Quote from: Folsom on 18 Aug 2016, 09:02 pm

1w is fine. Higher just means it's slower. It wont hurt anything.

Thanks

KR500 · « **Reply #490 on:** 19 Aug 2016, 01:20 pm »

Regarding the transformer, I used the Hammond 185F16 part
Yes , just checked and that is the same one I have . It is 3 and 3/8 inches tall and 4.25 pounds

walkern · « **Reply #491 on:** 19 Aug 2016, 02:29 pm »

I have the 185F16 transformer, and it WILL fit in the chassis. I used fairly thick rubber washers under the mounting tabs, and then added a layer of rubber damping under the transformer itself, and that bumped it up to a height where the top of the transformer was touching the top of the chassis. I went back in and removed the layer of rubber damping under the transformer, and got thinner rubber washers for the mounting tabs and re-mounted the whole thing with a thin layer of rubber damping on the top (last night), and now it is (a) not humming like it forgot the words, and (2) is not making the top of the chassis buzz. Whew!

So, go ahead and order up the cheap chassis if you like...(it comes stuffed with stuff that you need to gut, so it will require some effort on your part, and it will have some extra holes in the back and bottom) and know for sure that the transformer can be mounted in a fashion where it isn't making any audible noise. While I was in there I checked to see if the transformer could be mounted to the steel chassis divider (thereafter sitting sideways), and it will fit that way too (although without much room to spare... maybe 1/4 inch).

Sorry to have been reporting an issue that was my fault and not an actual problem with the chassis or transformer.

Neil

skrstc · « **Reply #492 on:** 22 Aug 2016, 08:29 pm »

Folsom thanks for your great little 7297 Chip Amp.

mlundy57 · « **Reply #493 on:** 22 Aug 2016, 08:48 pm »

Quote from: Folsom on 15 Aug 2016, 12:26 am

Yes you could connect the light to the AUX on the antipole if it fits the correct voltages the light needs. I don't know what light and what voltage it says, so I can't really answer that question.

The light is 12VDC

Quote from: Folsom on 15 Aug 2016, 12:26 am

You connect the two boxes before you ever turn it on, or discharge the capacitors on the Antipole before you connect it to the amp box. There's a place on the Antipole for a discharge resistor, but it might take a moment before they do. A 10k resistor would work.

Where does the discharge resistor go?

Would adding a 24VDC On/Off switch to the amp section be a viable alternative to the discharge resistor or would doing both, discharge resistor in the PS housing and 24VDC On/Off switce in the amp housing, be better?

Mike

S Clark · « **Reply #494 on:** 24 Aug 2016, 03:45 pm »

I've been very please with the sound of batteries, until last night. I don't know why, but when I connected power, my amp blew up... yep, both my 220 uF caps swelled and blew in seconds and all the magic smoke is now gone.

Folsom · « **Reply #495 on:** 24 Aug 2016, 04:56 pm »

Mike, it goes near the PSU caps where there's a symbol for a resistor. I wouldn't add a switch.

Scott that's terrible, did you reverse the polarity on accident? Generally that or severe over voltage can make caps explode. I doubt it was severe over voltage...

lacro · « **Reply #496 on:** 24 Aug 2016, 05:54 pm »

Quote from: mlundy57 on 22 Aug 2016, 08:48 pm

The light is 12VDC

Mike, I assume you mean it's an LED? Do you have any other specs or a link to the light (LED), and does it come apart?

S Clark · « **Reply #497 on:** 24 Aug 2016, 07:41 pm »

Quote from: Folsom on 24 Aug 2016, 04:56 pm

Mike, it goes near the PSU caps where there's a symbol for a resistor. I wouldn't add a switch.

Scott that's terrible, did you reverse the polarity on accident? Generally that or severe over voltage can make caps explode. I doubt it was severe over voltage...

Almost certainly. It was late, I was tired, ... But now I get to start over and upgrade parts!

mlundy57 · « **Reply #498 on:** 25 Aug 2016, 03:22 am »

Quote from: Folsom on 24 Aug 2016, 04:56 pm

Mike, it goes near the PSU caps where there's a symbol for a resistor. I wouldn't add a switch.

Jeremy,

Thanks

Quote from: lacro on 24 Aug 2016, 05:54 pm

Mike, I assume you mean it's an LED? Do you have any other specs or a link to the light (LED), and does it come apart?

Larry,

The light is built into the rocker switch, I guess it is an LED.

Quote from: S Clark on 24 Aug 2016, 07:41 pm

Almost certainly. It was late, I was tired, ... But now I get to start over and upgrade parts!

That's one way to look at it? Like the saying goes... "The difference between an ordeal and an adventure is your attitude"

Mike

Folsom · « **Reply #499 on:** 25 Aug 2016, 04:35 am »

Mike some switches run on 12v, some have resistors in them for 120v. Here's one that doesn't require you to mess around dropping the voltage to 12v. It's my go to for projects that don't have to be overly pretty.