i found this circuit online and was wandering what do the arrows at 7 and 14 mean?
http://www.zen22142.zen.co.uk/ronj/co2.html

 

It looks like 0 volts (ground) is connected to Pin 7. 12 volts is connected to Pin 14.

Those are usually Vcc and Ground pins on most chips in DIP package. The bottom left pin and the top right pin.

I take it they are using quad AND logic gate chip?

 

Yep. Here you go:
Pin 7 is Ground (0 volts).
Pin 14 is Vcc (12 volts in your case).

 

 

Hello,

@ shteii01,
The TTL chip you show will blow at 12 Volts.
MrChips has shown the correct pinout.

Bertus

 

Hello,

@ shteii01,
The TTL chip you show will blow at 12 Volts.
MrChips has shown the correct pinout.

Bertus

It is not my intention to tell OP which part/model number to use.

My intention is to show OP the function of certain pins. Pins 7 and 14 to be precise.

 

Hello,

There are also TTL chips with the power on the pins 5 and 10.
Have a look at some of the counterchips.

Bertus

 

Hello,

There are also TTL chips with the power on the pins 5 and 10.
Have a look at some of the counterchips.

Bertus

The OP schematic does not have power and ground on pins 5 and 10. Why should I waste my time on things that OP is not asking about.

 

Hello,

Always look in the datasheet/book to verify the right connections.
For more info on IC pinouts, you can have a look at this page:
http://www.kingswood-consulting.co.uk/giicm/

Bertus

 

The link shows "Cmos = 4081".

Able to work with up to 15 (or it is 18?) V.