Lil Watter amp

[gtangas]

Hi guys

finish the second build of this tinny amp.

First attempt was with a wood box


but i was having some hum on the circuit and so i jump to a metal chassis

I used a computer cd player chassis and start building!





Found a old sofa  and cut the tolex! lol 




Add a thunder puss circuit (used a mini toggle 3pdt switch that allows true bypass and standby middle position)


build a small pcb with the bridge rectifier and some caps for filtering the hum. The amp works at 12v and the thunder puss at 9v, so used two regulators to achieve these values.... Nice!




I know its a simple circuit but it was the first pcb that i draw from a schematic.

And to lay down these two boards i used a old pcb part and some pieces of a mouse pad to isolate.


and here it is!





the amp is nice to play with bedroom levels or even to plug the cell or an mp3 player.

I think i´m not getting the 1 watt because i bought the lm386l and not the lm386-3 or -4! The guy from the shop told me it was the same thing  but i thound in the web that this lm386l only gives 0.5watts. I already order the -4 from ebay and i expect to receive it next week

It was fun to build this one.... it was the first one with that special flavor!

But i want something with more power.

Any ideas? or nice projects for a full tube amp? min 5wt and not to expensive? we have the guys from Troika here in Portugal so.... hehehhe

[hoodoo]

Looks very nice mate, DIY at it's best.
Hope the missus wasn't too mad that you cut the sofa up went to a good cause.
Matt.

[nzCdog]

Wow looks great gtangas!  I like the tolex and corners, and the CD player chassis is a great idea! 

However....
I have top say that I have serious concerns about your wiring as it is!!!   

Having a mains transformer directly onto the chassis like that uncovered, poses a deadly electrical shock hazard.  The chassis mount transformer is designed to be enclosed within a device, not externally mounted...  Output transformers on the outside aren't so much of a problem, but mains transformers are.  Also you should definitely use a 3 conductor IEC connector with an earth connected to the metal chassis.  For your own safety PLEASE make some changes!

[nzCdog]

I am strenuously making these safety points as the Lil Watter design is to safely run off 12VDC, and your mains powered modification isn't safe in my opinion.  I know I sound like a killjoy, but I can't apologise.  People die everyday from electric shock and electrical fires, and your wiring looks dangerous.

[gtangas]

ok, no problem, i accept all the advice on a improving view and always with a smile.

I flip the trans and put the 220v on the bottom part. Used termal connection on all connections (i dont the know the english term, we call it manga termica) and on top of that i used hot glue to cover any possible situation.

Inside the chassis i used a closed plug for the 220v


Use a fuse as well

i can change the wire and connect the earth to the chassis no problem.

[spaceboss]

Agree with the above.

It's absolutely gorgeous   


and.....


don't kill your self. 

[gtr2]

extra points for reusing old stuff too!

[jeffaroo]

this will be your 2nd build. its a 20w solid state throw a sola tone bender in it and give it hell.   

http://musicpcb.com/pcbs/tiny-giant-amp/

[gtangas]

this will be your 2nd build. its a 20w solid state throw a sola tone bender in it and give it hell.   

http://musicpcb.com/pcbs/tiny-giant-amp/

I cant find a pcb layout to etch...

[hammerheadmusicman]

i Bought the kit for it, it fits in a 1590a! haven't got round to building it yet, but the kit is really cheap even with all the components..


good work on this build btw!

George

[nzCdog]

ok, no problem, i accept all the advice on a improving view and always with a smile.

Thanks Sergio, my concerns are only for safety, honestly I'm not trying to kill the fun

Inside the chassis i used a closed plug for the 220v

Sergio, I'm not 100% familiar with wiring standards for Portugal... If you have 3 conductors on your wall power sockets (2x power +  earth connection), then the earth wire should DEFINITELY be used to earth the chassis of your amplifier for safety.  If your wall socket only has two pins, then you should take EXTRA care to solder correctly every termination, making good mechanical and solder connection, and then DOUBLE insulate every high voltage connection heat-shrink rated at least 400V, preferably 500V+.

I flip the trans and put the 220v on the bottom part.

This style of mains voltage transformer mounting was traditionally inside an amplifier casing, not externaly exposed.   I have seen this style of construction in home made amps, it looks 'cool', but to my mind is dangerous.  The cloth and varnish covering the transformer windings is not designed as sufficient insulation for safe mounting outside a protective frame... so it is unsafe in my opinion, even though some builders do it. That's all I can say about that.

Used termal connection on all connections (i dont the know the english term, we call it manga termica) and on top of that i used hot glue to cover any possible situation.

From google I think your magna termica is what we call 'heat shrink'.  I would strongly recommend using 2 layers rated at least 400V+ over high voltage connections, ensuring it fits tightly and can't move at all.  Hot glue is NOT a sufficient insulator at high voltage for safety, neither is it suitable as a reliable mechanical tie for cables.  I recommend zip style cable ties to prevent the movement of cables and fatigue of solder connections.  Over time, poor connections will fail but good connections will stay intact.

i can change the wire and connect the earth to the chassis no problem.

As I mentioned earlier, if you have earth connectors at your wall socket, definitely use a 3 conductor power cord and connect your amplifier's chassis to earth.  This is an example of the IEC connector with a schuko plug, I'm not sure if it's what you have at home or not, but it has the 3 conductors with a separate earth connection.  

[gtangas]

ok, no problem, i accept all the advice on a improving view and always with a smile.

Thanks Sergio, my concerns are only for safety, honestly I'm not trying to kill the fun

Inside the chassis i used a closed plug for the 220v

Sergio, I'm not 100% familiar with wiring standards for Portugal... If you have 3 conductors on your wall power sockets (2x power +  earth connection), then the earth wire should DEFINITELY be used to earth the chassis of your amplifier for safety.  If your wall socket only has two pins, then you should take EXTRA care to solder correctly every termination, making good mechanical and solder connection, and then DOUBLE insulate every high voltage connection heat-shrink rated at least 400V, preferably 500V+.

Here in Portugal we only have two pin wall connections for the 220v.

I flip the trans and put the 220v on the bottom part.

This style of mains voltage transformer mounting was traditionally inside an amplifier casing, not externaly exposed.   I have seen this style of construction in home made amps, it looks 'cool', but to my mind is dangerous.  The cloth and varnish covering the transformer windings is not designed as sufficient insulation for safe mounting outside a protective frame... so it is unsafe in my opinion, even though some builders do it. That's all I can say about that.

yes i know. i place the trans outside because the vintage look or cool it gives. The tolex helps to prevent the proximity with the chassis

Used termal connection on all connections (i dont the know the english term, we call it manga termica) and on top of that i used hot glue to cover any possible situation.

From google I think your magna termica is what we call 'heat shrink'.  I would strongly recommend using 2 layers rated at least 400V+ over high voltage connections, ensuring it fits tightly and can't move at all.  Hot glue is NOT a sufficient insulator at high voltage for safety, neither is it suitable as a reliable mechanical tie for cables.  I recommend zip style cable ties to prevent the movement of cables and fatigue of solder connections.  Over time, poor connections will fail but good connections will stay intact.

ok, heat shrink, i use it in all my connections. on the power trans it as two layers of it. the hot glue was to cover that part to erase any possible situation. you cant see the wires from the trans with the hotglue.

even the inside bottom plate of the chassis have all surface with mouse pad so nothing can touch metal.

I can assure you that i have concerns about my (and others) safety... i dont want to get fried! 

Have you seen the question that i place on your post? lm386 in bridge? it would be nice to get 2w from this amp!

And to end as your started... FUN... i´m having a lot of fun with this little amp!now one of my guitars live on mu livingroom.. not that my wife likes but....    thx for that.

[alanp]

If you look at most externally mounted transformers on amps, they'll have metal covers over the ends, with holes on the bottom for the wires to exit (bell covers, I think.) So it will look (|||) kinda like that, with the bell covers bent 90 degrees at the bottom for feet.

[jeffaroo]

http://www.audioasylum.com/cgi/vt.mpl?f=kandk&m=8738

http://diyhifisupply.com/catalog/150

http://www.goodcomponent.com/transformer%20cover.html

[nzCdog]

I can assure you that i have concerns about my (and others) safety... i dont want to get fried! 

Have you seen the question that i place on your post? lm386 in bridge? it would be nice to get 2w from this amp!

And to end as your started... FUN... i´m having a lot of fun with this little amp!now one of my guitars live on mu livingroom.. not that my wife likes but....     thx for that.

Well have fun and be safe... You've got to make up your own mind the extent to which you will take the safety in the design.  I hope the livingroom venue lasts well for you... maybe learn some balads to serenade your wife so she warms to the new gear room idea   

http://www.audioasylum.com/cgi/vt.mpl?f=kandk&m=8738

http://diyhifisupply.com/catalog/150

http://www.goodcomponent.com/transformer%20cover.html

Those are cool