Assistance reading a schematic

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Joined: Wed Jan 03, 2018 9:06 am

Assistance reading a schematic

Post by Thomaswilliamrogers » Wed Jan 03, 2018 9:18 am


I am a total novice at reading schematics although I understand the concept to a basic degree. I’d like to build my own guitar effects pedal and have seen a couple of schematics. I generally understand the required components however I have seen on several schematics reference to pins with a voltage of 9V and 4V5, whilst there is also a battery and power connection.

Links below to the schematics where this occurs.

My question is what do I do with the pins with the noted voltage, is it simply a case of connecting them together and they will therefore each receive the required voltage from another part of the circuit, or do they require an additional power supply.

Example 1: You can see that there are 3 locations where the above occurs

Example 2: In this example the same occurs but with 2.4V and 4.8V

Any guidance (put simply) would be appreciated to help me work out how I put this together.

My intention is to etch my own PCB.


Posts: 220
Joined: Sun Oct 04, 2015 6:18 pm

Re: Assistance reading a schematic

Post by David » Wed Jan 03, 2018 12:34 pm

You are correct - all the 9v, 4,5v points and similarly with 4.8 and 2.4v on the second schematic should be connected together. If you are making your own PCB, be warned - not all of the essential connections may be shown on the diagram - some will be taken for granted. For example on the first schematic, no power connections are shown for U1 and U2; the +ve power should be connected to 9v (pin 4), and the -ve power to earth (pin 7) also, the common connection of D8, C17, R32, C16 and the power con(nector) should also be grounded. These are shown correctly on the second diagram.
The second diagram is not complete - The power con shows no connections, the voltage divider (R114, R115, C107) does not show how the bat (9v) has the voltage reduced to 4.8v. That will have something to do with Con7 - isolated at the top RHS.
Good luck. It might be a good idea for you to assemble the circuit of a breadboard before committing to a pcb.
Hope this helps.

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