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Currently out of stock on all DC Pulsed Controller (+ Tin) products. We will be sourcing more soon.

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DC Pulsed controller (to pulse an LED)

Pulsed controllers are often used with DC electric motors. At slow speeds motors tend to stall when powered from a simple variable voltage controller. But by pulsing the motor at full voltage we can overcome this and also provide a far more efficient way of driving the motor.

This is an example circuit for a simple pulsed power controller. Because this circuit only uses a small 741 op amp it can not directly control an electric motor.

So to test out the circuit you can just use an LED. Which is supplied. So using an LED what you see is the LED being switched on and off at the same voltage but this switching is at a high frequency. When the time it is on is much larger than the time it is off you then have a brighter light. When the time the supply voltage is off is much larger than the time it is on then the LED will appear far less bright. This is the pulsing effect.

Once you know that this little circuit works then you could replace the 741 with an external high power opamp (via hook up wire) installed on a separate vero board with heat sink, such as the LM675 or you could even just feed the output of this circuit into a very cheap pair of BGT transistors wired up as a darlington pair. Such a darlington pair arrangment is capable of driving a small 12 volt motor. (see video for an example of this)

By just using the LED, you can test out this pulsed controller circuit before purchasing the more expense hi-power op amp IC. This same circuit can be used for a 741 or a LM675 (with small modifications). The LM675 OPamp with a heat sink is nearly as expensive as this whole kit combined. So it is sensible to be sure the circuit works with an LED first. This basic easy to build circuit allows you to do just that. If you do buy the LM675 then you will need to make sure you use at least a 15volt supply to drive the higher power needed with this OpAmp.

Kit parts are as follows:
  • 2 of Resistors 10k
  • 1 of Resistor 22k
  • 1 of Resistor 390 Ohm
  • 1 of Resistor 1k
  • 1 of Capacitor 100nf
  • 1 of Electrolytic Capacitor 220uf
  • 1 of Capacitor 220nf
  • 1 of Potemtiometer trimmer 100k
  • 1 of 3mm LED
  • 4 of Diode IN4148
  • 1 of IC OpAmp LM741C
  • 1 of PCB board
  • 1 of Battery Clip
  • The tin (95mm x 60mm x 21mm)
  • Assembly instructions

The theory behind the circuit

The theory video is not required to get your circuit running. Those who are not interested in how the circuit works can just use the assembly instructions and refer to the second tin installation video for tips and an example on how to install the circuit within a typical enclosure. The theory is just an extra bonus video for those who like to know how their kits work.

NOTE: Video below is in HD quality so please view it in full size for best effect.

Tin Installation Video

NOTE: Video below is in HD quality so please view it in full size for best effect.


All kits that you buy will all come with a tin as an enclosure. (96mm x 60mm x 21mm) This short video goes through some suggestions on how to install your finished circuit into a typical enclosure. Often the tins used in the installation videos is a smaller tin for demonstration purposes. But you will always receive the larger tin version.