Hi,
I'm trying to build myself a basic amplifier to use with my PC as some may already know from my questions about a couple of ICs to do the job previously.
I've now switched to the TDA2005 IC to do the job. Yet again, though, although it amplifies, there is tremendous noise and pulsing coming from the speakers. It is away from interference and I've tried alternative power supplies and audio inputs. So, three different amplifier ICs and the same trouble each time...
With this IC, there is a hobby circuit available all over the net which uses a similar circuit to the one I was copying, so I tried that - same problem. Then I noticed that on one site selling the kit, they said this:
"We spent a lot of time getting the tracks right on this single sided PCB to get the lowest possible THD. Getting the separate tracks to the earth pin is the secret."
Could someone please explain what THD is and would it sound like what I have complained of: noise, pulsing, but mainly loud static noise?
Anyway, I'm now wondering if the problem with all the circuits has been my layout. I'm using Eagle to do it, and it autoroutes with thin tracks which I thicken but it doesn't allow for easily making areas of copper on the PCB, and I haven't done so anyway as I didn't know it was necessary or where it was necessary.
I am going to try and do my homebrewed PCB with the exact component placement and as similar copper layout as I can see on the hobby kit's PCB picture as possible in the hope this will do the trick. But why are these amplifier circuits so fussy? I gather it's the grounding that's the trouble - my thin tracks running all over the place to ground components dotted about randomly is not good, instead big thick ground parts running around the edge of the PCB are needed with the component sides that need grounding actually imposing into this copper area where possible. But why? Whether this way or a thin track running to it, there's still an electrical connection, isn't there?
Someone please help educate me :roll:
Thank ye
I'm trying to build myself a basic amplifier to use with my PC as some may already know from my questions about a couple of ICs to do the job previously.
I've now switched to the TDA2005 IC to do the job. Yet again, though, although it amplifies, there is tremendous noise and pulsing coming from the speakers. It is away from interference and I've tried alternative power supplies and audio inputs. So, three different amplifier ICs and the same trouble each time...
With this IC, there is a hobby circuit available all over the net which uses a similar circuit to the one I was copying, so I tried that - same problem. Then I noticed that on one site selling the kit, they said this:
"We spent a lot of time getting the tracks right on this single sided PCB to get the lowest possible THD. Getting the separate tracks to the earth pin is the secret."
Could someone please explain what THD is and would it sound like what I have complained of: noise, pulsing, but mainly loud static noise?
Anyway, I'm now wondering if the problem with all the circuits has been my layout. I'm using Eagle to do it, and it autoroutes with thin tracks which I thicken but it doesn't allow for easily making areas of copper on the PCB, and I haven't done so anyway as I didn't know it was necessary or where it was necessary.
I am going to try and do my homebrewed PCB with the exact component placement and as similar copper layout as I can see on the hobby kit's PCB picture as possible in the hope this will do the trick. But why are these amplifier circuits so fussy? I gather it's the grounding that's the trouble - my thin tracks running all over the place to ground components dotted about randomly is not good, instead big thick ground parts running around the edge of the PCB are needed with the component sides that need grounding actually imposing into this copper area where possible. But why? Whether this way or a thin track running to it, there's still an electrical connection, isn't there?
Someone please help educate me :roll:
Thank ye