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Do-it-yourself pedal building

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Not a pedal but some audio DIY

Fri Jan 19, 2018 5:08 pm

My hifi amp didn't make it to France for some reason so for 4 months I've been listening and dancing to Macbook speakers.... :barf:

I don't really like to buy cheap new stuff from China but I'm on a tight budget down here and at £2 for a 2 x 15w chip amp my principles were superseded. I already had the 14.8v lithium RC car battery for my street amp project which can power it directly for a long time. I've got 2 sets of charity shop speakers here - some 70s Celestions I found in London for £12 and a pair I found today for about the same price - some modern Magnat speakers that are £100 new and can handle 60w rms. They aren't as cosy sounding as the Celestions but sound good at volume and can reproduce a whole band of treble that the old Celestions can't keep up with.

Aside from the PCB, the rest of the build was made with street salvage.

I'm impressed by the sound. It does its job very well.

Got another PCB on order so I'll build something properly mobile with the Magnats and use the Celestions in the house I think with a wall power supply.



Re: Not a pedal but some audio DIY

Fri Jan 19, 2018 5:46 pm

:joy: :thumb:

Pretty sweet man.

Re: Not a pedal but some audio DIY

Fri Jan 19, 2018 6:17 pm

Looking for cheap secondhand 12v transformers I found some lots of LED lighting ones.

Any reason I might have overlooked why these wouldn't power one of these little amps?

https://www.ebay.co.uk/itm/Low-Voltage- ... Swg31aW2Wg

EDIT: YES! They output AC. :picard:

2nd EDIT: Looks like the TDA7297 accepts AC or DC though :joy:

3rd EDIT: I have a feeling these need a minimum load to work. It says 20-60w which I'm thinking means it wants at least 20watts running through it.

Re: Not a pedal but some audio DIY

Thu Jan 25, 2018 5:28 pm

Just to make sure this thread doesn't become at all interesting.....here's a 12v regulator I put together tonight. The 14.8v lithium pack actually kicks out over 16v when fully charged. I'm also gonna try to use this to start my motorbike tomorrow.



Re: Not a pedal but some audio DIY

Thu Jan 25, 2018 5:56 pm

I shouldn't really be allowed to do electronics.

The LM7812 is only rated to 1A and I think the amp wants more.

A motorcycle must also want way more than that.

And the LM7812 should be good up to 18v....
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