[Questions] TDA2040 on 9v with FET preamp ... good idea ?

[seadi123]

I'm planning to build a simple amp with a TDA2040 chip and a FET preamp , that will run on 9v . I will use the schematic on the datasheet for the power amp and the Till Discrete FET preamp in front of it . Does it sound like a good idea ?

I'm just looking for clean guitar sound that does not clip , that can be loud enough to be clearly heard in room for practice . I would like this amp to be pedal friendly . I think i can put this in a 1590a enclosure . Can i use the enclosure as a heatsink ?

I've had a bad experience with the lm386 which clips at high volumes , but the TDA2040 would give me almost 4W with a 9v supply . Can i use regular 9v adaptors as power supply ? Also can someone explain me the +Vs , -Vs and Vi on the schematic ? Thanks

[mth5044]

The TDA2040 is expecting a bipolar supply. +Vs is the positive side, -Vs is the negative side, Vi is in the input. The black bars are ground. You would also have to make sure your power supply can give it enough current. A charge pump, giving you +/- 9V, won't have enough current.

I don't think this will work with that chip.

Check out the Tiny Giant project by Taylor, it is close to what you are looking for. I'm working on a project for a power amp IC from Tayda currently, could be used with a 9V, I'll make a project of it if it works. Awaiting the package to arrive.

[tca]

Try the PUNCH amp

[merlinb]

I'm planning to build a simple amp with a TDA2040 chip and a FET preamp , that will run on 9v . Also can someone explain me the +Vs , -Vs and Vi on the schematic ?

Yes it will work- see figure 12 in the datasheet you linked to (the figure is mis-labeled, it's actually single rail, not split supply).

the TDA2040 would give me almost 4W with a 9v supply . Can i use regular 9v adaptors as power supply ?

A 9V supply can't give you more than 2.5W into 4 ohms, less in reality. Still enough for practice volume though. (Fig. 3 in the datasheet is for a bipolar supply- notice it says +-Vs on the x-axis)
2W into 4 ohms is 0.7 amp rms, so one of the bigger standard wall warts would do.

Can i use the enclosure as a heatsink ?

Yes, and it looks like you can get away without an insulating kit too, because the tab is connected to V- (ground in your case). According to the datasheet the device will dissipate about 8W when shoving 2W into a 4ohm load. An aluminium enclosure will cope with this, since you won't be dissipating it continuously anyway.

[bool]

Don't waste your time (and the TDA2040 chipamp). It simply wasn't made to work with 9V supply, but to be used in home stereos etc. where there's enough juice available.

Better use the TDA2003, a cheap chipamp that works well and reliable and was tailor-made to work with 11-14V automotive (car-radio) supplies and will work down to 9V. (TDA2002 is also a good candidate, practically identical to 2003). Both chips can tolerate some abuse...

Save your TDA2040 for a slightly more advanced future project of yours .. once you get bored with the TDA2003.

EDIT: With TDA2003/TDA2002 you don't have to isolate the heatsink from the circuit's "V-" (ground, negative ... ), because the chip was "made this way", i.e. for use with single-polarity supplies.

[sajy_ho]

I tried TDA2040 and TDA2003 both with 9V supply, TDA2003 was pretty loud but the sound was a little muddy. 2040 was a good sounding chip but in 9V it was less than half the volume of 2003. TDA2003 was designed for car radio and is a low/mid fi amp but TDA20X0 series are hifi chips and better to be used in guitar amps; many of cheap SS guitar amps using them in power amp section. among TDA20X0 series only 2040 can work with single 9V supply. If you're not much into hi volume, a jfet pre into a 2040 would give a nice practice amp! use the schematic shown in figure 10 of the datasheet and don't forget to use load protective diodes.
here's a good instruction that I used:http://www.ssguitar.com/index.php?topic=16.0

[PRR]

TDA2040 is made for 30V-40v total supply.

It may "work" at 9V. There are better choices.

The old LM386 is pretty good at 9V 8 Ohms 1 Watt.

The old-old '2003 is very good at 9V 4 Ohms 2 Watts. (However is getting hard to find?)

With a responsive speaker, a Watt or two is plenty to annoy your parents/lover/children.

With 4 Ohm load on 9V supply, the average supply current for sine-wave output is 0.4A (half the average load current), perhaps as high as 0.6A for steady gross over-drive. Half that for 8 Ohms.

[tca]

I've had a bad experience with the lm386 which clips at high volumes...

ALL those chips will badly clip at high enough inputs. I'm convinced that these chips should not be overdriven.

With a responsive speaker, a Watt or two is plenty to annoy your parents/lover/children.

+1

The LM386-3 is almost "unbeatable" for battery operated <=1W amplifiers.

[PRR]

> lm386 which clips at high volumes...

ANYthing will clip at high enough volume. I just pencilled a 5,000 Watt amp and a way to clip it. (I want to annoy my annoying neighbors a mile down the road.)

True, the LM386 clips nasty. The TDA2003, by design or accident, clips less nasty; good, because it (was) used a lot in car radios and some folks clip them constantly.

[Brymus]

The LM486 is a dollar at Mouser and puts out a clean (.1%) distortion at 1W with 5V supply. IIRC
The LM386N4 is also a dollar at Mouser and will put out a clean 1000ma but needs 16V to do so,but can be ran at 18V (2 x 9V battery)
What I like about the 386 IC's is (to me) they overdrive nicely as you increase the gain,kinda like an old tube amp does.

[PRR]

8 ohm load at 16V is a LOT of current for 9V batteries.

Also a lot of heat for an 8DIP.

So maybe the "overdrive" you get is battry sag. (And waste of battery energy and price.)

LM380 is a better chip for 18V work. More pins to throw the heat. Still brutal for 9V batts.

[Brymus]

Yeah,I need to correct myself...
It is the LM4861 not 486 and it will output 1.5 watts into 4 ohm load at 1% THD+Noise or less at 5.5V its a 6V max IC.
It does 1.5 watts at 10% THD into 8 ohms or 1 watt 1% THD 8 Ohms.
This is at 100hz to 20Khz fine for guitar use.
http://www.mouser.com/ds/2/405/snas095c-286490.pdf
Its made for PC use where there is a huge current available at 5V,still a 9V 1A wart with a 5V regulator should suffice.

If he really wants to use the TDA2040 I would think 2 wall warts wired bi polar would work,wouldn't it as long as they are both rated the same current output?
I know(would guess) most of us have several 9V wall warts around the house.

[garcho]

That's what AC (output) wall warts are for. 9vac can be rectified into +\- 9vdc. Easy to find 12-18vac wall warts, too. Of course, wall warts are rarely more than an amp or two...

[JebemMajke]

8 ohm load at 16V is a LOT of current for 9V batteries.

Also a lot of heat for an 8DIP.

So maybe the "overdrive" you get is battry sag. (And waste of battery energy and price.)

LM380 is a better chip for 18V work. More pins to throw the heat. Still brutal for 9V batts.

Has anyone ever tried to make a high gain distortion with lm380?