personal audio amp

[audioguru]

I think he used a 25V-0V-25V transformer by mistake.

 

[audioguru]

Oh yeah, Philips have about 76 IC amps and ST Micro also have 70.
Maybe they are available in your country.
**broken link removed**
http://www.st.com/stonline/stappl/p...type=4&tname=TL_DATASHEET_TREE_X_DOC&latest=N

 

[baftab]

variable dual power supply
max +35 to min -35
i thght it is needed in so many circuits..why not make sumthin tht can be used over and over

thnx...i look into these ics...

 

[Nigel Goodwin]

variable dual power supply
max +35 to min -35
i thght it is needed in so many circuits..why not make sumthin tht can be used over and over

It's doubtful if it's powerful enough to run audio amplifiers?, they take a fair amount of power - unless you've built it with huge heatsinks and descrete regulators?.

 

[baftab]

LM 337 and LM 317
is it enuff?
or should i add something more to it?
no heatsinks though...
i'll add them

 

[Nigel Goodwin]

LM 337 and LM 317
is it enuff?
or should i add something more to it?
no heatsinks though...
i'll add them

NO!, far too small, Audioguru mentioned that earlier - also you should fit as large a heatsinks as you can, because even at fairly low currents they will get really hot at lower voltages.

Try doing the maths - W=VxI.

With 35V in, and (for example) 12V out, you're dropping 23V across the IC. If you draw 1A then the IC is dissipating 23x1=23W as heat. With 0.5A, it's 23x0.5=11.5W - with no heatsink it will probably only handle 1-2W?.

 

[baftab]

how about this one?
it'll give me + - 22 but thts enuff for me
no voltage regulators.. though

 

[audioguru]

Audio amps don't need voltage regulators.
The LM317 and LM337 supply 1.5A only when their output voltage is near their input voltage. They reduce their output current when they are set to lower output voltages to protect themselves, only 150mA.

Of course they need heatsinks with fins, because power= VI.
If your heatsinks aren't big enough, the regulators will shut-down when they get too hot.

 

[baftab]

i wish you guys were my teachers

thnx
btw where did you guys graduated from?

 

[Nigel Goodwin]

i wish you guys were my teachers

thnx
btw where did you guys graduated from?

The simple PSU you posted is like the one I mentioned earlier, it's all that's needed for an audio amplifier.

Personally I never graduated from anywhere :lol:

I left school at 16 and went to work doing radio/TV repairs, after the first year I started attending technical college on day release, one day a week.
It was a four year course called ETV, I skipped ETV1 and started directly in ETV2 (as I already had O Level physics), I passed ETV2 with distinction and went to ETV3, I passed ETV3 with Distinction Grade 1 (the higher mark they gave). Because of this high mark I skipped ETV4 and moved to a technicians course in the third year, called T3 - this was a six or seven year course (as fas as I can remember?).

Anyway, this was a seriously BAD move - T3 was a complete waste of time!, I was learning nothing, and just wasting a day and night of my life every week, so after the Christmas break I stopped going any more :lol:

So I never actually finshed ANY electronics course :twisted:

This hasn't stopped me being Sharp UK TV Service Engineer of the year twice, and Grundig UK Satellite Engineer of the year once 8)

 

[baftab]

:shock:
wow!!!!!!!!!!!!!
now that is an achievement
hats off for you
i did O levels too
but didnt left schooll...did A levels too...now doing Electronics Engineering

4 yr course...

 

[audioguru]

My teachers didn't have much to teach me about electronics, but I taught them a lot. :lol:

 

[baftab]

lolz
which uni or college?

 

[audioguru]

Ryerson University in Toronto, Canada.

 

[baftab]

now am making this
and hav absolutely no idea what it is...other than that it is an amplifier

tell me...oh please tell me....is it Class A config or CLass B or what?
i am using an 8ohm .5watt speaker? is it enuff?

 

[Nigel Goodwin]

now am making this
and hav absolutely no idea what it is...other than that it is an amplifier

tell me...oh please tell me....is it Class A config or CLass B or what?
i am using an 8ohm .5watt speaker? is it enuff?

It's class B or class AB, it's also a VERY poor design, for many reasons - but a 0.5W speaker would be fine.

 

[audioguru]

Wow! You've found a very powerful audio power amp design.
I've done some numbers-crunching on it and I figure that it will give a whopping power into the speaker of 15.6mW.

You might hear something if you turn up the volume and hold the speaker directly to your ear. :lol: :lol:

 

[audioguru]

I built this amp for my son's alarm clock. It has nearly 10 times the power of yours from its little 8-pins IC.

 

[audioguru]

My 150mW amp has poor bass response.
Replace the 0.1uF cap in series with the 3k resistor at pin 4 with 4.7uF.
I have edited the schematic. :lol:

 

[Nigel Goodwin]

My 150mW amp has poor bass response.
Replace the 0.1uF cap in series with the 3k resistor at pin 4 with 4.7uF.
I have edited the schematic. :lol:

Isn't the internal circuit of the chip wrong as well?, the input is shown connected to the non-inverting input of BOTH amps.

I suspect there should be no connection there?, but a second 125K to the non-inverting input of the top amp.