Chipamp: TDA2030 + output transistors

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Hello

I found this chip-amplifier circuit last week and I would like to try it out.

The OTL amplifier listen comfortably by TDA2030 and TIP41+TIP42 | Eleccircuit.com

Do you think it would be possible to substitute the output transistors with a pair of BD243/BD244 medium-power transistors? The part list shows TIP31/TIP32 as replacements, it has the same max. current rating as BD243/BD244 (3 A).

Is the common point of diodes D1 and D2 supposed to be connected into the pin #4 of the amplifier IC? It seems unnecessary just to connect them like shown on the schematic, reverse-biased from Vcc to GND.

Could an old laptop charger be used to power this circuit? The one I have is rated at 18,5 VDC and 4,17 A.
 

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I do not think i would try that.
You have a 18.5 volt supply.
check out TDA8560Q.
You will need to drop the supply voltage a bit, most probably 2 diodes will do.
18 volts is the maximum those chips can take.
They are rated for 2 ohm load, and have arepetative peak output current of 7.5 A.
Very nice chip, and its stereo.

If you drop the supply voltage to something close to 17 volts then it will deliver more than enough power. Essentialy inside the chip a verry similar setup is to be found as Yours.
The bonus is that You do not need to findle with transistors, it is allready stereo and BTL,
has diagnostic output, and mute functionality.

As for quality, most likely You will like its sound.
At 16 volt supply voltage the datasheet shows (f = 1khz, Rl = 2 ohm) 0.5 % THD at 35 watt output power.
Quite a lot from a simple chip!
 
Thanks for your suggestion!

I also have this amplifier IC that was disassembled from a broken car receiver (the amp IC still worked). The markings on it are very faint, but it seems to be a TDA7386. Do you think it would be roughly comparable? Its datasheet lists the output power as 4 x 16,5 W at 0,8 % THD into a 4 Ω load.
http://electronica.grulic.org.ar/documentos/tda7386.pdf

I can imagine that it might be useful in a small active two-way system when paired with some simple op-amp filters. But that's a bit outside my scope.

Actually I don't mind fiddling with transistors if there's a chance that it might work well. I have already used a TIP32 transistor in the power supply of another small chip amp circuit.
 

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that is allso a quite good chip.
Do not fear the 16.5 W output is quite decent.
allso, that spec. is for 13.2 volts supply voltage.
You should go for something close to 17 volts.
(mentioned allready, needs to drop the PSU voltage a bit to not kill the IC)

In that case it will deliver a lot more power with less distorsion.
even if it would not, remember, that 2x10 watts of power is far more than needed for an avarage living room, given efficient speakers.

If You would boost the tda2030 with transistors, the resoult would only be marginaly better.
The supply voltage limits the output swing, and naturaly the output power.
Biasing error of the transistors might even result in LESS output power and far worse sound.

Go with this chip, You will be quite surprised.
I ran on tda1557Q a pair of 8 ohm rated 3 way floorstanders, on a 12 volt supply.
And it still had enough juice to be very loud.

Give the chip 1uF decoupling caps at the input, and add a 220 pf ceramic from input to ground.
As for powersupply, drop the voltage with diodes.
now, SMPS has the habit of voltage overshooting when turned on, it might kill this IC.
There fore I would adwise a dummy load for startup, and a relay to connect the power to the amplifier a short time after the PSU has been turned on.
Search for delayd relay on google to find schematics.
Porbably a very short time is enough to allow the PSU to stabilise.
 
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