Voltage Multiplier

I have a question.. I am relatively new to the world of electronics, so new that I in fact just learned how to apply ohms law to make sure I don't burn anything up anymore. So I'm wondering if this is an actual property of a DC power supply? and why isn't it going through the other leg of the relay to complete the circuit? Electricity takes the path of least resistance, right? I don't get why it's going through the LEDs instead..

The other leg is just a volt meter, it doesn't complete the circuit because it has infinite resistance. Also its best to note, electricity takes ALL paths of resistance.

Hi D264, as rich has said, the other leg just has a voltmeter which has infinite resistance in the simulator. If it helps you to understand the circuit just remove the voltmeter. Now, at the onset, current will flow from the 4V supply through the relay contact and also through the LED’s. However, the current flowing in each branch will depend on the nature of components in each branch. The relay coil has a resistance of 100 Ohms so current will be around 40mA in that branch. The current in the other branch is negligible - reason is that we only have a 4V supply whilst three LED’s in series require 6V (2V each).

When the relay contact switches a back emf is generated which (in series with the 4V supply) is sufficient to cause the LED’s to light (briefly). I hope this answers your question.

In case you are not familiar with back emf: current flowing through a coil creates a magnetic field. If the current is interrupted (in this case by the relay contact opening) the magnetic field collapses and generates a voltage (emf) that tries to keep the current flowing. However, since the relay contact has opened, the current goes through the LED’s instead.

Interesting comments Rob.. Thanks for such excellent commentary. It helps people to get better learn the EMF nature.