First Lm3886

[Stuey]

Originally posted by PJPro

Sorry Stuey, which one do you mean? The ESP?


Yes, Thanks. I did look at that....but it was a bit scant on the information.

Yes, the ESP one. Although it's quite complex for what it does! Just one thing, Rod Elliott's boards are cheap - it might be best to grab one rather than fiddle round yourself. He's very helpful, too, and provides comprehensive instuctions, plus you get access to more info on his 'sealed site' via password. (in the interests of full disclosure, ESP's boards aren't as neat as many out there, but with the sheer number he produces, who can complain? I don't think any of us can imagine now an internet without ESP, one of the 'go-to's' for information in our hobby.)

Likewise, if you ask Greg Ball on the Ska site, he'll reply within hours, usually. And although a very clever man, he doesn't talk down to you like many do in that position... I'm in contact with him most days via the Ska forum.

Cheers

Stu

[PJPro]

OK. I think I'll get a few of the soft start circuits from ESP along with the transformer I identified earlier.

I've also bought three Epsilion 24 PCBs to allow me to use anti vandal power switches.


Epsilion 24 Schematic


Bulgin Anti Vandal Switch

If I can, I'm going to power the Epsilion 24 circuit using the transformer provided to power the soft start circuit. Not sure this will be possible. The Epsilion 24 requires 12VAC while the soft start needs 9VAC. I've bought Sigma 24 PCBs just in case (these are usually unavailable, so I don't mind if I don't have to use them for these amps).

I'll get some big caps for DC blocking on the input. I've had a recommendation from Ted205 for Ampohm. Are there any other recommended caps for placing in the signal path?

Also, does anyone have any views on the ferrite beads? Good idea or bad?

I've had a look for inductors. Can anyone have a recommend a particular type? Has anyone used one in their build? The data sheet seems to suggest the inductor is used to counter capacitance due to long speaker cable runs (mine will be short). Will they also serve a RF filtering function? Grateful for any views on inductors.

[Stuey]

Bloody hell PJ, you better like these amps!

[Stuey]

Hi PJ,

I went into the ESP secure site (not 'sealed' ) and had a look for you. The relays have a 12V coil, and are rated at 10A (SPDT switching). Rod uses ones marked FRM1-1C1 which he describes as having a universal footprint. If you Google this number you get plenty of hits.

FYI.

Stuey

[PJPro]

Originally posted by Stuey
Bloody hell PJ, you better like these amps!

Well, my intention is up upgrade them over time by using discrete amp circuits and improved power supplies.....while keeping the transformer, switch and soft start the same. So, I'm keen to get the bits I'm not going to change right first time.

Moreover, it gives me a chance to experiment and to try and understand/experience as many different circuits as possible in the run up to building a B22 headphone amp with a Sigma 22 power supply and (in my dreams) a brace of B24 power amps.

Incidentally, I've got a Starving Student headphone amp kit arriving any day now from Beezar. I like these kits cos everything you need is supplied in the kit. Makes life a lot simpler . See here.


Starving Student kit by Beezar.com

[PJPro]

Originally posted by Stuey
Hi PJ,

I went into the ESP secure site (not 'sealed' ) and had a look for you. The relays have a 12V coil, and are rated at 10A (SPDT switching). Rod uses ones marked FRM1-1C1 which he describes as having a universal footprint. If you Google this number you get plenty of hits.

FYI.

Stuey

Thanks Stuey. But a quick search on Farnell and RS didn't return any hits!

[PJPro]

Errrr. Seems these relays aren't that easy to get over here. See here .

[Stuey]

I think these may suffice. They simply need the same footprint and ratings.

http://www.jaycarelectronics.co.uk/p...T&SUBCATID=754

Edit: I just realised the 2C2 is a DPDT and that photo on Jaycar is just indicative, so that IS the right one IMO. See the link below where the -2C2 is rated at 2 x 5A (ie. douple pole) and both types have the same photo. So I'd suggest the -1C1 is the SPDT variant 1 x 10A which is what you need. Note Jaycar used the same photo for the DPDT, cat no SY 4052.

http://www.dt.com.au/category.php?cat=ELECT:COMP:RELAY

Many of the Aussie electronics businesses (like ESP) buy from Jaycar wholesale (called Electus) further suggesting that this might be the one.

Stuey

[pacificblue]

Those advertising texters are really killing me. "Elegant relays"

[Stuey]

Originally posted by anatech
Hi PJPro,
The circuit shown in the EDN article for discharging the supply capacitors should never have been printed - anywhere! There is no electrical safety organization that would ever pass it. That is one reason we used to see the really expensive switches with the larger DPDT section in front and the smaller DPDT switch mounted further back.

-Chris

Interestingly, that won the Grand Prize for the best design idea for 2001...and the designer won $1,500!