So i've been playing around with this amp and actually ive had really good results! however i do have a few questions for the smart ones as im stuck.
1. The amp when no sound is going through seems to occasionally "pop" or "crackly" so to speak random and it is like something is randomly interfering with it, this happens randomly
2. When the pot is turned up it goes way to loud im unsure how to affect this.
3. This is the oddest one! I have a 100uf cap between the power input and ground, this helps with decouple (i think that is what it is called) however when ever i need to turn it on, i have to remove this cap, pull the power cable out, switch the power on then place the power cable back in and then place the cap back in. Otherwise it acts like it shorts and just wont turn on 😵
So a few other things, i followed this schematic,
http://www.build-electronic-circuit.../2013/05/stereo-amplifier-circuit-diagram.png
And this is currently built on a breadboard.
I should also point out, the .15uf is not eh same as the one in the schematic, ive used a polarised one, does this matter? Also the same with the .22uf cap
Thanks again chaps!
1. The amp when no sound is going through seems to occasionally "pop" or "crackly" so to speak random and it is like something is randomly interfering with it, this happens randomly
2. When the pot is turned up it goes way to loud im unsure how to affect this.
3. This is the oddest one! I have a 100uf cap between the power input and ground, this helps with decouple (i think that is what it is called) however when ever i need to turn it on, i have to remove this cap, pull the power cable out, switch the power on then place the power cable back in and then place the cap back in. Otherwise it acts like it shorts and just wont turn on 😵
So a few other things, i followed this schematic,
http://www.build-electronic-circuit.../2013/05/stereo-amplifier-circuit-diagram.png
And this is currently built on a breadboard.
I should also point out, the .15uf is not eh same as the one in the schematic, ive used a polarised one, does this matter? Also the same with the .22uf cap
Thanks again chaps!
TEA2025 voltage gain is 45dB or nearly 200.
Power amps for home hi-fi usually have gain nearer 20.
A gain of 200 amp casually built on breadboard *will* magnify all stray electric clicks in the environment and loose joints on the breadboard.
> when ever i need to turn it on, i have to remove this ca
What power supply? Many switching supplies do not like large caps.
Power amps for home hi-fi usually have gain nearer 20.
A gain of 200 amp casually built on breadboard *will* magnify all stray electric clicks in the environment and loose joints on the breadboard.
> when ever i need to turn it on, i have to remove this ca
What power supply? Many switching supplies do not like large caps.
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You may have a linear pot instead of a log type volume control.
At tha center of rotation, the resistance from the wiper to ground should be
much less than half the total value of the pot.
Is there a way I can lower the gain? Finding circuits for it is a pain, I have a log type pot on it.
I should note that when the 100uf is on the ground and positive it prevents it from cutting out at loud volume, remove it and poof! It cuts out...
I should note that when the 100uf is on the ground and positive it prevents it from cutting out at loud volume, remove it and poof! It cuts out...
Yes you can lower the gain from the standard but not by a huge amount or it'll go unstable. The datasheet explains it - you need resistors in series with the caps on pins 6 and 11.
Ah excellent! I'm going to assume it will tell me in the data sheet what ohm resistors I will need, oddly enough I did try it and got some improvements, I will update later with results!
It needs a little familiarity with feedback amplifiers - the long and short of it is to get the minimum recommended gain (36dB or X63) you need those resistors to be 110ohm.
Okay I tried it with 480ohm resistors and an array of others ha, thanks for the input guys will see how it reacts later when I finish work and hopefully solve it. Then it's onto why it won't switch on with out me having to remove stuff first o.0
I did it! i actually did it 😀 very first amp i have built which sounds good doesn't have ripple popping and i can turn up without it cutting out!
So thank you all very much!
I added the 18k in there which resolved the stupidly loud sound which just crackled away, i dont actually have any 120 or 110 ohm resistors so i decided to try out some 240 and 480 ohm resistors. They seem to work i dont notice to much difference and iu seem to be able to go full volume without them. Sorry can someone remind me why they are there?
But still i built this thing with what i feel is limited knowledge on the subject and self taught research i feel really proud and now ready to take the next step and build it onto a pcb.
So thank you all very much!
I added the 18k in there which resolved the stupidly loud sound which just crackled away, i dont actually have any 120 or 110 ohm resistors so i decided to try out some 240 and 480 ohm resistors. They seem to work i dont notice to much difference and iu seem to be able to go full volume without them. Sorry can someone remind me why they are there?
But still i built this thing with what i feel is limited knowledge on the subject and self taught research i feel really proud and now ready to take the next step and build it onto a pcb.
if you like this chip,
then maybe you can consider .. bulding a btter powersupply,
and attempt an sta540 chipamp 🙂
verry simular to thisone but it has better stats and vastly moar pooowa.
then maybe you can consider .. bulding a btter powersupply,
and attempt an sta540 chipamp 🙂
verry simular to thisone but it has better stats and vastly moar pooowa.
Ha thanks arty. It will be the next adventure for me 🙂
On a side note, is it normal to have a slight hum/buzz when the jack is plugged into a audio source when it is built on a breadboard? Or do I need to adjust something somwhere?
On a side note, is it normal to have a slight hum/buzz when the jack is plugged into a audio source when it is built on a breadboard? Or do I need to adjust something somwhere?
a high gain amplifier like this on a breadboard can pick up a lot of "stuff" so i would not consider it a huge flaw.
most possibly shorter traces and a better powersupply (less ripple) and probably a bit of work on the grounding side of things can silence it.
i suppose its main's hum coupling into the input, if its 50-60 hz ish kind of noise, that is.
you can verify it with an online tone generator set to 50 hz, if it sounds like the buzz you hear then we got our suspect.
most possibly shorter traces and a better powersupply (less ripple) and probably a bit of work on the grounding side of things can silence it.
i suppose its main's hum coupling into the input, if its 50-60 hz ish kind of noise, that is.
you can verify it with an online tone generator set to 50 hz, if it sounds like the buzz you hear then we got our suspect.
I did a little research on it and came to that conclusion but just wanted to get abit of a confirmation, next question! Half of the ice is dead 🙁 it's suitable for two 8 or 4 ohm speakers, so I reckon I will build it bit only build one side, this should be okay shouldn't it?
It's more to do with practical tests to get used to building them etc, will it ever be used? Maybe, maybe not but still! It's an amp I could use in a small portable speaker etc, I'm unsure but o reckon it's power draw is pretty low so shouldn't be to bad
my more or less portable party box has an sta540 with 2 channels bridged, and one mroe sta 540 in bridge+paralell (4 amps "merged" into 1 channel) running from 3x6 volt alarm batteries in series (about 18-20 volt or so) and will do an overnight party without problems.
the stereo one drives 2x2 17" fullrange speakers, while othe otherone drives a subwoofer i re-wound for 1.5 Ohm impedance. no problems. heavy as hell, but the thing fits nicely in the trunk, 2 people can transport it with ease, and is powerfull enough to give a decent experience in open field for 20 ish people.. rocks the place properly.
the stereo one drives 2x2 17" fullrange speakers, while othe otherone drives a subwoofer i re-wound for 1.5 Ohm impedance. no problems. heavy as hell, but the thing fits nicely in the trunk, 2 people can transport it with ease, and is powerfull enough to give a decent experience in open field for 20 ish people.. rocks the place properly.
I didn't know you could put amps into parallel, how do you do that? Also do you have any pics of your party box or a link to a build thread?
Gain calculation is on page 4 of the datasheet
http://www.unisonic.com.tw/datasheet/TEA2025.pdf
Ignore the "JWC1" term; this expresses the low-cut, not the passband gain.
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