Lighting House

This circuit can be used for a flashing light transparent plastic toy. A good example is a transparent plastic house toy, thus the name of this Instructable.

Please read this article from beginning to end if you are going to build this circuit at home.

PSpice simulations software student edition.

The circuit consists of a Schmitt trigger oscillator and a non-inverting operational amplifier. You can google Schmitt trigger oscillator to find how to calculate the frequency of oscillation. There are many articles on this topic online.

Calculate the maximum LED current:

Saturation voltage Vsat = 1 V:

IledMax = (Vs - Vsat - Vled) / Rled

= (9 V - 1 V - 2 V) / 470 ohms

= 0.01276595744 A

= 12.76595744 mA

Saturation voltage Vsat = 2 V:

IledMax = (Vs - Vsat - Vled) / Rled

= (9 V - 2 V - 2 V) / 470 ohms

= 0.01063829787 A

= 10.63829787 mA

You can use a dual LM747 operational amplifier if you are going to build this circuit.

Simulations show that the current is high because the operational amplifier model has a low saturation voltage.