There doesn't appear to be anything wring with the PCB layout.
However I don't know about the schematic because you've drawn the op-amp as a box rather than using the proper symbol.
The box is meaningless and it means you need to keep refering to the datasheet, in order for the schematic to make sense. If you use the real op-amp symbol then the schematic will make sense, without having to look at the datasheet and it will be easier to read too. **broken link removed**
You are missing the 47uf capacitor to ground at the junction of the 1k and 10k resistors.
A 78L08 won't work from a 9V battery that drops to 6V. It needs a minimum input of 10V.
The circuit does not need a voltage regulator.
If the output connects to a shielded cable then a 100 ohm series resistor at the output must be used to isolate the capacitance of the cable to avoid oscillation.
So in other words i can scrap the regulator and just power from a 9v battery?
Thanks for pointing out the missed cap, I dont know how I missed that.
I have yet to work out the output stage, Im not sure if you remember but I want to use the output to activate a transistor to act as a switch for a RF encoder input. - Thats the next challenge to overcome
Yes because the regulator's input voltage is too low for it to regulate and all it will do is make the supply to the opamp about 7V without regulation when the battery is new and less when the battery runs down.
The 100uf capacitor filters the battery voltage pretty well.
Back to the output stage I've been thinking again (although im not sure what kind of voltage/current the amp will put out).
In your opinion what i be best off using a transistor to act as the switch, a phototransistor, or a coil to activate a reed switch?
I have never used a reed switch so I don't know the current in the coil.
If it is 100mA or less then a transistor can easily drive it and the base current of the transistor is 10mA or less which most opamps can drive.
You need to limit the base current to the transistor and maybe add a diode so it does not become too negative.
The relay coil needs a reversed diode across it to arrest voltage spikes.
Non-polarised capacitors tend to be used more <1µF and for 100nF there's often no choice but to use a non-polarised capacitor because 100nF electrolytic capacitors are rare and probably more expensive.
Film capacitors should also be used wherever possible because they have lower distortion than ceramic or electrolytic capacitrors.
You need to limit the base current to the transistor and maybe add a diode so it does not become too negative.
The relay coil needs a reversed diode across it to arrest voltage spikes.
I have never used a reed switch so I don't know the current in the coil.
If it is 100mA or less then a transistor can easily drive it and the base current of the transistor is 10mA or less which most opamps can drive.
You need to limit the base current to the transistor and maybe add a diode so it does not become too negative.
The relay coil needs a reversed diode across it to arrest voltage spikes.
I was just wondering if you knew of a transistor I could look at because there are so many.
for example would a BCV47 do it? Im not really sure what I should be looking for on the data sheet, but from what I gather it could handle the power requirements?
You must match the transistor to your reed relay.
You selected a tiny darlington transistor that is only 3mm long. Maybe you cannot connect to its tiny pins.
It is a darlington type that has a fairly high voltage loss.
The tracks need to be as thick as possible.
That makes teh track impedance less.
It also makes desoldering much easier so you dont suck the tracks off with the desolerinmg tool.