How to Turn a Small Lamp on and off with a PC


   It may seem like a simple enough task given the enormous power ofUSB automation adaptor allowing a PC to switch 14 outputs on and off the PC and the simple nature of the task, but it still requires a certain minimum of knowledge and information to hand. For the purposes of this task we will use the MiniBee Automation Adaptor.

    Firstly we will see how to connect the lamp to the MiniBee and then how to use the BeeStep control software to switch the lamp on and off.
   When connecting anything to a switching device like the MiniBee it is important to ensure the voltage and current requirements of the device (lamp) are within the specified limits of the MiniBee. In our case we will be attaching a 9v lamp which takes 200mA of current. The MiniBee is rated at up to 50 volts with 500mA maximum per output which makes it easily suitable. The connection diagram below shows how the lamp is connected.
how to connect a small 9v lamp to a PC so it can be turned on and off under PC control

    For the purposes of clarity a photo of this connection arrangement is also shown below
connecting a 9v lamp to a USB adaptor board to provide PC control

    As you can see from the connection arrangement we have an external power supply (a battery) which is supplying the 9v required to turn on the lamp. If the connections going to the MiniBee terminals were removed and connected together the lamp would be permanently on. I.e. the MiniBee is forming a break in the circuit until the PC instructs it to switch on. It is important to note the polarity of the connection shown. By that I mean which terminal of the battery is connected to the GND terminal of the MiniBee. This should always be the negative battery terminal. The positive battery terminal is always the one which is connected to the lamp (or in fact any other device to be controlled such as a motor ) .

    Now the MiniBee should be connected to the computer using a standard USB lead. This may be to a hub or directly into a USB socket on the PC itself.
USB connection of an adaptor board for switching high voltage loads with a PC

    As soon as you connect the MiniBee Windows will normally alert you to the fact that something has been connected by making a short two-tone sound. This lets you know everything is okay with the USB side.
    Assuming you have installed the MinBee software on the installation disk, it is now time to run it. The software BeeStep14 provides a means of creating a full control system sequencing the on and offs of up to 14 independant devices, but for our immediate purposes we will focus on just the one lamp.
simple control software for switching a 9v lamp on and off under PC control

    The first thing to do is to tick the box which says “use MiniBee”. This instructs the software to actually cause the switches on the MiniBee to operate when specified. (without this tick you can test sequences on the screen first to make sure they are correct before actually switching external devices).
software details for switching a bulb using a PC
    Also tick the “Mimic On” box which makes the screen display mimic the on and off of the outputs displaying a red box for on and green for off for each of the 14 outputs.

    All we need to do now is specify a very simple control sequence that switches the lamp on and off repeatedly. This is done by specifying a “step” with the lamp on followed by a “step” with the lamp off. A step is just a combination of the on/off setting for each of the 14 outputs with an associated duration, which in our case will be 2 seconds.
    To create a step with output 14 (our lamp) on, just click the button associated with output 14 and it will turn red to indicate "on"…

    Then enter a duration of 2 seconds using the edit boxes …
sequence control for switching DC devices using a PC with a usb adaptor board
    Now add this to the sequence list using the add button….

    Click on button 14 again turning it off (green) and then the Add button again.
    You can repeat this until you have a few steps with alternate on and off of output 14. When ready, you just click on the “run” button and you should see the lamp turning on and off. At the same time you will see each of the steps you specified getting highlighted in turn as the sequence progresses.
simple automation sequence software for a PC
    The sequence will stop when it gets to your last step. If you want to make this continuous you can change the “next” sequence to use entry for the last step to the number of the first. This will cause the entire sequence to be repeated.


!!!!    You are now switching a lamp on and off under PC control     !!!




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