Archives December 2013

Kirchoff Laws

Kirchoff law consists of two laws relating to electronic circuits.

The two laws are named after Gustav Kirchoff, who described them in 1845.

Law one deals with Current (I) within a circuit, and law two deals with Potential Difference which is also commonly known as Voltage (V).


The current entering any junction in a circuit (i.e a component connection point on a PCB) is equal to the current leaving that junction point.

To state this law algebraically we can state:


Before you run away screaming, I will explain how to understand the algebraic equation above.

The thing that looks like a bit like a drunken ‘E’  is called an epsilon. It means the total addition of the currents entering and existing the point in a circuit.

‘I’ is the symbol for Current

‘n’ is the total number of connections (or branches) flowing towards, or away from the particular point in the circuit (known as the node point).


The Sum of all the voltages around the loop is equal to zero.

V1+V2+V3 – V4 = 0

Where V4 is the Voltage supply.

Vehicle Ammeter

Vehicle Ammeter add on accessory suitable for a wide range of vehicles including 4×4.

The Ammeter is used to measure current (I) drawn through a circuit, and indicates up to 30 Amps.

Please ensure that the equipment that you intend to connect it to, does not draw more than 30 Amps current.

An ammeter is important for monitoring how much current is being drawn by your circuits. An ammeter is connected ‘in series’ .

The best way to imagine a series connection is to think of two people holding hands. These two people are a wire between the battery / voltage supply , and the piece of equipment.

To fit an ammeter, you connect it between the hand of each person. If you are not competent to do this, then consult an auto electrician.

Once you have your ammeter connected, it will display the current(in amps)that the piece of equipment connected after the ammeter (the end persons other ‘free’ hand.

Reasons that you would want to know the current drawn is if you have added accessories to your vehicle, such as a 4×4 winch. This may mean that the current drawn exceeds the current supplied by the charging system when lots of electrical systems are on simultaneously.

Example of electrical systems include headlights, air conditioning, rear heated windscreens.

We are a Uk supplier, and aim to dispatch within three days.  For more help and information, contact Craig via  my business website