Loud Speaker?

[ChrisGreece52]

Thanks for the answer.
So bottom line i must pay great attention to the heatshink .
I need the simplest way of all suggested above
Also i had not the fear of electrecution until now thanks for that

[mariush]

You'll have mains electricity only up to the terminals of the transformer. You isolate those with electricians tape, heatshrink, whatever.

The outputs of the transformer 24v ac, or +15v , -15v etc are all floating. It's also low voltage so it's not really a safety risk unless you put your tongue on it or something like that.

You just have to know that the metal back of the chip is connected to what would be -15v on your power supply.  Traditionally, circuit boards are grounded to what they're screwed on (ex on motherboards ground in the connector coming from the psu is connected to the metal case through the screws sometimes) so if you do that and the metal heatsink touches the metal case you have a short circuit.
If you put the prototyping board and the heatsink in a plastic box (abs) the heatsink is basically not touching or shorting anything, so you don't need insulation. And if you touch it with your hand, at best you're going to feel some tingling in your fingers and the chip may reset or make awful noise (you're may short the -vs to ground through the big resistor your body forms)

[madires]

Also i had not the fear of electrecution until now thanks for that

You're welcome! 

[madires]

You just have to know that the metal back of the chip is connected to what would be -15v on your power supply.  Traditionally, circuit boards are grounded to what they're screwed on (ex on motherboards ground in the connector coming from the psu is connected to the metal case through the screws sometimes) so if you do that and the metal heatsink touches the metal case you have a short circuit.
If you put the prototyping board and the heatsink in a plastic box (abs) the heatsink is basically not touching or shorting anything, so you don't need insulation. And if you touch it with your hand, at best you're going to feel some tingling in your fingers and the chip may reset or make awful noise (you're may short the -vs to ground through the big resistor your body forms)

I'd suggest to mount the TDA isolated if the heatsink isn't inside any non-conducting box to prevent trouble with the input signals. Putting a 15W heater inside a closed plastic box isn't a good idea IMHO. The best way is to place the heatsink at the backside of the speaker box for proper air convection.

[ChrisGreece52]

The outputs of the transformer 24v ac, or +15v , -15v etc are all floating. It's also low voltage so it's not really a safety risk unless you put your tongue on it or something like that.

If you put the prototyping board and the heatsink in a plastic box (abs) the heatsink is basically not touching or shorting anything, so you don't need insulation. And if you touch it with your hand, at best you're going to feel some tingling in your fingers and the chip may reset or make awful noise (you're may short the -vs to ground through the big resistor your body forms)

Damn i was looking forward to licking a transformer  
Anyway ill be carefull and i will insulate the terminals (after soldering them) with tape and then heatshrink tube (just to be extra sure) as for the case i will go with a wooden box so no insulation needed .

[ChrisGreece52]

You just have to know that the metal back of the chip is connected to what would be -15v on your power supply.  Traditionally, circuit boards are grounded to what they're screwed on (ex on motherboards ground in the connector coming from the psu is connected to the metal case through the screws sometimes) so if you do that and the metal heatsink touches the metal case you have a short circuit.
If you put the prototyping board and the heatsink in a plastic box (abs) the heatsink is basically not touching or shorting anything, so you don't need insulation. And if you touch it with your hand, at best you're going to feel some tingling in your fingers and the chip may reset or make awful noise (you're may short the -vs to ground through the big resistor your body forms)

I'd suggest to mount the TDA isolated if the heatsink isn't inside any non-conducting box to prevent trouble with the input signals. Putting a 15W heater inside a closed plastic box isn't a good idea IMHO. The best way is to place the heatsink at the backside of the speaker box for proper air convection.

Ill think of installing 2 small 40mm fans so they keep the box cold

[mariush]

No need for that man.

Just drill some holes in the case where the bottom of the heatsink should be, and some holes towards the top, somewhere above the heatsink.
Hot air tends to rise up, so colder air will be sucked in through the holes at the bottom and the warm air will get out through the holes at the top ... it's called natural convection : https://en.wikipedia.org/wiki/Convection

If it will get really hot, get a regular 80mm - 120mm that you can find basically anywhere and put it to blow the warm air OUT of the wood box .. you can power it directly from 15v through a dropper resistor to get the fan running at 6-8 volts so that it won't be noisy.

[madires]

Ill think of installing 2 small 40mm fans so they keep the box cold

Passive cooling rulez! :-)

[ChrisGreece52]

No need for that man.

Just drill some holes in the case where the bottom of the heatsink should be, and some holes towards the top, somewhere above the heatsink.
Hot air tends to rise up, so colder air will be sucked in through the holes at the bottom and the warm air will get out through the holes at the top ... it's called natural convection : https://en.wikipedia.org/wiki/Convection

If it will get really hot, get a regular 80mm - 120mm that you can find basically anywhere and put it to blow the warm air OUT of the wood box .. you can power it directly from 15v through a dropper resistor to get the fan running at 6-8 volts so that it won't be noisy.

That would save me time thank you

[smashedProton]

Yes, if your speakers are well made you can venture past their rated values.  But I would not do that.  Also, be sure not to clip your amplifier.  That is very bad stuff that will burn up the coil.  Remember that speakers are not ac driven heating elements.  Also, the best way to get more output is RESONANCE.  Make a ported box.  T-lines are also good because they can cause the backpressure to constructively interfere with the foreward.

[jmacqueen]

Wow what a thread, why not something like the old pignose amp circuit ala 1970's. great for guitar practice, easy to build, should be able to get transformers and even the other components  from scrap electronics like old car stereos or old busted radios.  Been used for years and years now.. by all the greats. not hard to make, playing with different transformers to get the drive and tone you like..

schematic... http://music-electronics-forum.com/attachments/2913d1218923726-pignose-model-7-100.gif

[ChrisGreece52]

Wow what a thread, why not something like the old pignose amp circuit ala 1970's. great for guitar practice, easy to build, should be able to get transformers and even the other components  from scrap electronics like old car stereos or old busted radios.  Been used for years and years now.. by all the greats. not hard to make, playing with different transformers to get the drive and tone you like..

schematic... http://music-electronics-forum.com/attachments/2913d1218923726-pignose-model-7-100.gif

cool but i dont think it will work with bass guitar.... i am a bit comfused thought ... i really want to make the amp myself and dont buy one already made ....

[cais]

Hola buenas tardes, tengo una placa igual y quisiera usarla, pero no dispongo del esquema de conexiones en las borneras, sería tan amable de facilitarmela. Muchas gracias

[cais]

Hello good afternoon, I have an equal plate and I would like to use it, but I do not have the connection scheme in the terminals, it would be so kind to facilitate it. Thank you

Hola buenas tardes, tengo una placa igual y quisiera usarla, pero no dispongo del esquema de conexiones en las borneras, sería tan amable de facilitarmela. Muchas gracias

[Zero999]

Hello good afternoon, I have an equal plate and I would like to use it, but I do not have the connection scheme in the terminals, it would be so kind to facilitate it. Thank you

Hola buenas tardes, tengo una placa igual y quisiera usarla, pero no dispongo del esquema de conexiones en las borneras, sería tan amable de facilitarmela. Muchas gracias

Please create your own thread, rather than bumping a really old one.