EMRFD Message Archive 1940
Message Date From Subject 1940 2008-08-14 10:57:21 gi0gdp IC Audio amps vs Discrete
audio amp, i think a TDA2002. Well it was hard on the batteries and
didn't sound all that good. Recently having some time on my hands i
extracted the audio stages from the old FT-221R and did a spice
simulation. I then built the circuit on a PCB and was very pleasantly
surprised. Excellent for battery power and a good exercise in playing
with spice, and excellent sound quality. The only down side is that it
takes up more space than its IC equivalent.
regards
Geoff Pike
GI0GDP1942 2008-08-14 12:04:01 John Levreault Re: IC Audio amps vs Discrete
45ma, and a max of 80. Possibly as much as the rest of the radio. This
is not unusual for many audio amps originally designed for car audio. (I
think the TDA2002 goes back to around 1978.)
Just for a comparison, the NJM2135 I referred to earlier has a quiescent
current of only 2.7ma, typically. And you can certainly do that with
discretes.
de John NB1I
gi0gdp wrote:
>I remember building a handheld transceiver for 70cm and using an IC
>audio amp, i think a TDA2002. Well it was hard on the batteries and
>didn't sound all that good. Recently having some time on my hands i
>extracted the audio stages from the old FT-221R and did a spice
>simulation. I then built the circuit on a PCB and was very pleasantly
>surprised. Excellent for battery power and a good exercise in playing
>with spice, and excellent sound quality. The only down side is that it
>takes up more space than its IC equivalent.
>regards
>Geoff Pike
>GI0GDP
>
>
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>1946 2008-08-14 18:54:11 Johan H. Bodin Re: IC Audio amps vs Discrete
there are many good op-amps around that will easily drive headphones, or even a
small speaker. For example, TS922 from ST is a cheap dual op-amp which can drive
up to 80mA peak, even if powered by +5V. This is more than enough for low-Z
headphones. The TS922 has an equivalent input noise voltage of 9nV/sqrt(Hz) so
it is much quieter than many so called "audio amplifiers"... Current consumption
is around 2mA. It is a true op-amp, stable down to unity gain, so hiss filtering
can easily be achieved by putting some "C" in the feedback network.
TS922 is quite old, newer/better/cheaper chips may exist today. In my shack, the
LM386 days are over (as are the NE612 days) ;-)
72
Johan SM6LKM1948 2008-08-15 08:57:38 ehydra Re: IC Audio amps vs Discrete
5watts, x53A with 1W and x52AT and 57AQ. They are very different so
consult datasheet. They go up to 300kHz, short-circuit and
overtemperature proof. The price is around 1 Euro.
You can make audio amps, small motor driver or any driver apps up to
300kHz...
Don't need caps in the signal path!
Most types have DC logarithmic volume control. Some mono, others stereo.
SMD, DIP or SIL available.
Downside is that they don't have a shutdown supply current mode.
regards -
Henry
--
www.ehydra.dyndns.info1949 2008-08-15 08:57:41 bobtbobbo Re: IC Audio amps vs Discrete 1951 2008-08-15 09:36:03 Leon Re: IC Audio amps vs Discrete
1952 2008-08-15 15:47:51 ehydra Re: IC Audio amps vs Discrete
chip stops power supply current?
I'm not sure. The DS doesn't detail internals :-(
An added app is as differential driver.
- Henry
Leon schrieb:
> ----- Original Message -----
>1953 2008-08-15 20:19:00 Leon Re: IC Audio amps vs Discrete
1954 2008-08-15 20:51:54 Leon Re: IC Audio amps vs Discrete
>1955 2008-08-15 23:28:42 jr_dakota Re: IC Audio amps vs Discrete 1958 2008-08-16 10:06:49 Dan Reynolds Re: IC Audio amps vs Discrete 1959 2008-08-16 14:49:05 ehydra Re: IC Audio amps vs Discrete 1962 2008-08-17 18:22:18 Dan Reynolds Re: IC Audio amps vs Discrete 1966 2008-08-18 12:44:41 ehydra Re: IC Audio amps vs Discrete 1968 2008-08-18 12:44:46 cwfingertalker Re: IC Audio amps vs Discrete
Looks like the TDA7052 would be a good choice for QRP battery driven
radios. Probably a better substitute for the LM386 in new projects.
The spec sheet has all the information you need. You can find that in
the obvious places.
For a good visual look how simple the amplifier can be check this link
out.
http://www.electronics123.com/s.nl/it.A/id.405/.f
Cheers.
73
Bill N7EU1972 2008-08-19 23:45:37 Dan Reynolds Re: IC Audio amps vs Discrete
I looked at the data sheet and couldn't believe that was it.
What's the DC volume control option?
I saw those in Mouser and others...
Thanks.
Dan - KB9JLO
[Non-text portions of this message have been removed]1974 2008-08-20 09:12:54 ehydra Re: IC Audio amps vs Discrete
volume with an extra DC controlled pin. Think of the equation:
OUT = IN multiplied by antilog(DC_volume_pin)
Humans hear the loudness logarithmic.
Now you can steer volume by microcontroller -> PWM -> lowpass-filter ->
DC_volume_pin
Hope that helps -
Henry
Dan Reynolds schrieb:
> Henry / Bill, yes it looks too simple!--
>
> I looked at the data sheet and couldn't believe that was it.
>
> What's the DC volume control option?
>
> I saw those in Mouser and others...
>
> Thanks.
>
>
>
> Dan - KB9JLO
>
>
>
> [Non-text portions of this message have been removed]
>
>
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www.ehydra.dyndns.info1979 2008-08-20 18:00:34 ehydra Re: IC Audio amps vs Discrete
I just measured what is going on in Mute=silence mode= pin 5 voltage is
0 volts.
My test device was a TDA7052A (with DC volume control pin).
Unfortunately it doesn't reduce current consumption in Mute and outputs
never go in high-impedance mode (at least as long as it is not in
temperature shutdown).
That would be useful functions and I hoped to find such functionality there.
BTW: The signal input pin is always approx. half the power supply voltage.
I think that behavior is all over in the TDA705x family.
regards -
Henry
Leon schrieb:
> ----- Original Message -----
>