TDA2030 help!

[dataplex]

hello

last year i got a lot of help from you guys regarding an ebow circuit design. i ended up building a slightly modified 18v LM386-4 circuit like this ::

**broken link removed**

its an "electronic bow" for strings, basically a pickup and driver coil that feedback through a string, making it sustain a note for as long as the circuit is turned on. i made a micro-controlled electromagnetic harp that has 13 circuits like the above, switching strings on and off....

the project was great, but now i want to improve the circuit, and make it more powerful.

any thoughts on the TDA2030? i have it laying around, but don't really have the proper knowledge to implement it into a working design....

the LM386 distorted the signal a lot, and was only returning around 9v into the driver coil - resulting in very slow attacks on the tones of the string, or just no response at all.

the circuit needs to be compact to fit inside the new instrument, and not too expensive... powerful, for better response and less distortion.

any ideas? ANYTHING is helpful, my knowledge is limited, but im resilient as hell.

thanks!!

 

[dr pepper]

The 2030 is a good chip, maybe not an audiophile type device.
The 2050 is an improved version.
The things you need to be most concerned about are load impedance has to be higher than the 2030's minimum and heatsinking.

 

[dataplex]

hey dr pepper, thanks for the reply!

okay.... so, how would i apply the 2050 to a function similar to the above schematic?

 

[audioguru]

The LM386 circuit provides a maximum output of 6V peak-to-peak into 8 ohms when it is clipping like mad with 10% distortion (almost a square wave). Its output is 5.35V p-p when its output is as high as possible into 8 ohms without clipping. Then simple arithmatic shows that its power is very low.
If its load is less than 8 ohms or its power supply voltage is less then its output voltage and output power are even less.

The TDA2030 provides more power into 8 ohms when its power supply voltage is much higher than an LM386. It needs a heatsink.

 

[bountyhunter]

With only a single 9V battery, neither IC will put out much power. You could use the TDA2030 with dual supplies (two 9V batteries) but the batteries won't give a whole lot of operating time. As I recall, typical quiescent current n a 2030 is something like 40 mA. When operating, that goes up significantly depending on load impedance.

I can't tell from the schematic what the load impedance is or what frequencies you are trying to drive and what signal level must be driven. Without that info, you can't design anything.

 

[davenn]

hey dr pepper, thanks for the reply!

okay.... so, how would i apply the 2050 to a function similar to the above schematic?

download the datasheet for the TDA2050 and it will have example schematics with all the component values for you

Dave

 

[unclejed613]

the frequency range would be for a guitar, if he's making an e-bow.... that would be about 80hz to 4khz or so. the original e-bow worked on a single 9v battery, so the active drive current wouldn't have been much more than 50-100mA

 

[bountyhunter]

Without info on the characteristics of the load it's driving, noway to know what's going on.

 

[dr pepper]

Good point, you can play tunes on a barbecue grille with a commercial ebow, raises the question as to why is so much power needed.
Maybe the transducer isnt very effecient, might be worth looking at that first.
The 2030 wouldnt be able to put out max power on 9v with a proper load impedance, and if it did it'd kill a pp3 in minutes.
If you do go with a 2030/50 then your gonna need to run from aa's.

 

[dataplex]

hey guys

im running the circuit on 18v, using hand woven 200ohm humbucker pickups, and 8 ohm driver coils.
the frequency range is for guitars, like unclejed said.

heatsinks aren't an option im afraid, since the amps will be enclosed in a very tight wooden box. but maybe the LM386 isnt the problem... maybe its the driver coils...
perhaps he driver coils aren't woven correctly, here is an image of them :: https://imgur.com/Vu0YT

i did not count the turns as i used a power drill to wind them. however they all measure at 8 ohms. maybe the coils are a little too elongated? would a coin shaped coil make a better driver?

the TBA820M does not require a heatsink, is this chip something worth looking into? anyone experienced with it?

thank you all,
úlfur

 

[bountyhunter]

heatsinks aren't an option im afraid, since the amps will be enclosed in a very tight wooden box.////
the TBA820M does not require a heatsink, is this chip something worth looking into? anyone experienced with it?

thank you all,
úlfur

The heatsink requirement has nothing to do with what IC you choose, it is (as I said before) dependent on the load impedance the chip is driving and the signal level you are trying to drive into that load. It's strictly a power dissipation issue which is defined by the load and driven output, not the IC doing the amplifying and driving.

The TBA820 is rated for less than 2W power, I doubt that is sufficient based on what you have posted. You need to specify what the output signal level is and calculate power, then calculate power dissipation in the driver IC.

If you choose an IC that can not use a heatsink, and then try to drive significant power, the IC will just melt.

 

[audioguru]

Why are you using a supply that is as high as 18V? Then with a high output level the little amplifier IC will melt.

The datasheet for the LM386 shows its heating with 6V, 9V, 12V and 16V supplies.
With a 6V supply, its output power is only 0.25W and its heating is 0.21W.
With a 9V supply its output power is 0.56W and its heating is 0.52W.
With a 12V supply its output power is 0.66W and its heating is 0.82W.
With a 16V supply its output is about 0.7W and its heating is 1.4W.
If the ambient is 30 degrees C (it will be higher when enclosed) then the IC overheats when its heating is more than 1.1W.

The datasheet for the TBA820 shows that it also gets extremely hot when its supply is as high as 12V and does not show higher supply voltages.

 

[dataplex]

hey audioguru

im using lm386-4n, which is rated up to 18v. they heat up a little bit, but have never melted or gone bad! i opted for 18v to get maximum output to my handwoven 8ohm driver coils.

i really want to experiment with the TBA820.

if someone could demonstrate a schematic that:
-uses a TBA820 to amplify a signal from a 3k neodymium Humbucker pickup
-drives an 8 ohm neodymium driver coil, with a frequency response of 20hz - 4khz
-runs on 16v, outputting around 2watts?

if this is not possible, id love to hear why, so i can learn a little more about audio electronics and parts...

 

[audioguru]

The datasheet for the TBA820 shows that with a 16V supply its output is 2W with horrible 10% clipping distortion and it is extremely hot WHEN NOT ENCLOSED.
Like ALL little amplifier ICs.

Instead you should use a TDA2003 amplifier IC that has a case with a cooling tab and has an output of 4W into 8 ohms when its supply is 16V and the output has 10% clipping distortion. Cool it with a small heatsink.

 

[dataplex]

thanks audioguru! that sounds a lot better...

any ideas where i could find a schematic for the TDA2003 that could work for this particular application?

best,
ú

 

[dataplex]

perhaps this one?

https://www.hobby-hour.com/electronics/tda2003-power-audio.php

 

[dataplex]

sorry for making all these posts... but does this schematic make any sense to you?

View attachment 66126

 

[audioguru]

You should always look at the datasheet of the manufacturer who invented an audio amplifier IC.
The Hobby-Hour schematic is copied from the datasheet.
The LM1876 amplifier IC is for high power and has a minimum supply of 20V. Its circuit is missing a few important parts and it has an extra opamp for sensing output current which is not needed.

 

[cachehiker]

Coils will increase in resistance if the winding tension is too high.

A little something I've learned working with motors.

 

[cachehiker]

BTW, the amp connected to this laptop is a bridged TDA2030A design at about 2x30 to 2x35 Watts depending on your "yardstick" powering a pair of vintage JBL Decade 16 2-ways with 8 inch woofers. They sound awesome.

I have another amp based upon the same TDA2030A, unbridged, at work powering a pair of better than the micro-boombox POS speakers that were was being used prior to my bringing the amp in.

I've found them to be bombproof with a reasonable heat sink.

View attachment 66157