Hello,
i want to build an amp based on lm1875 and planning to etch board by toner transfer method. Schematic is from datasheet. just want to sure if i had a mistake on pcb and learn some possible improvements. Here is pcb;
feedback resistors and 0.1 uF bypassing caps are underneath the board.
thanks.
i want to build an amp based on lm1875 and planning to etch board by toner transfer method. Schematic is from datasheet. just want to sure if i had a mistake on pcb and learn some possible improvements. Here is pcb;
An externally hosted image should be here but it was not working when we last tested it.
feedback resistors and 0.1 uF bypassing caps are underneath the board.
thanks.
well, a more readible layout is here. any comments?
An externally hosted image should be here but it was not working when we last tested it.
You might have trouble with noise the way you are laying the PCB out. You seem to have connected all the grounds to the ground plane, where as these chips perform better if built using a star ground point to ground everything.
Basically you want to establish a ground point (the star ground)on the PCB and connect your 0V from your PSU there along with the speaker ground. Then you want to run all of your power grounds (from the caps) to that point SEPARATELY from the low level input signal grounds which also attach to that point. This should minimize the chance of ground related noise.
If you search this forum you will see many PCB designs for different chips that use this method that you could adapt from.
Basically you want to establish a ground point (the star ground)on the PCB and connect your 0V from your PSU there along with the speaker ground. Then you want to run all of your power grounds (from the caps) to that point SEPARATELY from the low level input signal grounds which also attach to that point. This should minimize the chance of ground related noise.
If you search this forum you will see many PCB designs for different chips that use this method that you could adapt from.
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