Help with circuit diagram

Hi, im fairly new to electronics, i dabbled a bit when i was younger so know basically what a resisotr does, a capacitor etc etc.

I want to make this simple circuit

**broken link removed**

The 12v will be from the +ve on a car battery. Am I right in thinking this will work in place for the "regulator"

**broken link removed**

Apparently thats rated at 12v to 8v step regulation.

Also does the -ve mean the - from the battery? and 0 volts = ground?

Lasty when looking for capacitors they had 22nf ones but they had different voltage regulations, 50v, 100v etc, not really sure what one i need :\

PumaSteve said:

Hi, im fairly new to electronics, i dabbled a bit when i was younger so know basically what a resisotr does, a capacitor etc etc.

I want to make this simple circuit
The 12v will be from the +ve on a car battery. Am I right in thinking this will work in place for the "regulator"


Apparently thats rated at 12v to 8v step regulation.

Also does the -ve mean the - from the battery? and 0 volts = ground?

Lasty when looking for capacitors they had 22nf ones but they had different voltage regulations, 50v, 100v etc, not really sure what one i need :\

Click to expand...

hi,
The 7808 is a +8V regulator ~1Amp.
The -ve is from the 'low' end of the ignition coil. the one that goes the contact breaker contacts.

0V is vehicle chassis. assuming your vehicle has the negative end of the battery connected to the chassis.

The caps should be ok at 50Vwkg or 25V

Not sure what this means..

The 12v will be from the +ve on a car battery. Am I right in thinking this will work in place for the "regulator"

Click to expand...

Hi brilliant thanks for clearing some of that up, so the 7808 would suit this situation?

With regards to me now knowing what exact components i need if someone could just do a brief list of the ratings of stuff i need then i should be able to work it out from there

PumaSteve said:

Hi brilliant thanks for clearing some of that up, so the 7808 would suit this situation?

With regards to me now knowing what exact components i need if someone could just do a brief list of the ratings of stuff i need then i should be able to work it out from there

Click to expand...

Hi,
You do realise its a RPM voltage output.?

yeah, excuse my lack of knowledge but how does that effect the compenents im choosing

PumaSteve said:

yeah, excuse my lack of knowledge but how does that effect the compenents im choosing

Click to expand...

it was this phrase that I didnt understand.

The 12v will be from the +ve on a car battery. Am I right in thinking this will work in place for the "regulator"

Click to expand...

EDIT:
The 7808 requires these extra components.

thank you very much for your help

ooh one more quick thing, thats outstanding, anyone know where a suitable place to take the -ve from the car would be? the car is distributor less ignition, so has a coil pack not a distributor cap.

PumaSteve said:

ooh one more quick thing, thats outstanding, anyone know where a suitable place to take the -ve from the car would be? the car is distributor less ignition, so has a coil pack not a distributor cap.

Click to expand...

The LM2917 is a "Frequency to Voltage" convertor, so it can accept many kinds of inputs. Check the wiring harness schematic for the car. For those that have a distributorless system, there's usually a takeoff on the harness providing either a pulse or a voltage for a tachometer. The LM2917 can accept a 6V to 8V input pulse. Just change the 20K resistor on the input to match.