There’s a new plug at Jee Labs – one I’ve been waiting to use myself for quite some time – a dual MOSFET plug:
The IRLZ34N’s used here should be able to drive over 5A @ 50V, but this will require a heatsink. For use without heatsink, a maximum currrent of 1 .. 3 amps should work fine. Just keep in mind that MOSFETs can generate a few watts of heat when used continuously at 2A or more. You can tie the MOSFETs in parallel for larger currents. You’ll need to add protection diodes to switch inductive loads, such as DC motors, relays, and solenoids.
This plug was designed for driving LED strips, but other loads can be driven as well. With two MOSFET Plugs, there are 4 individually controllable switches – to drive an RGB strip and a white strip, for example.
The terminal blocks used on this plug are heavy duty and detachable and use a standard 0.2″ grid (5.08 mm). They are much more convenient than fixed terminal block, particularly if the plug is mounted high or in some remote spot behind a book case or curtain. The two outputs have separate connectors.
The traces on this board have been made extra wide to be able to handle large currents flowing through the terminal block pins. The pins are laid out as two pairs: one side must be tied to ground, the other side (+A or +D) is then tied to the load, which in turn gets connected to a positive supply voltage (3..50V). Note that the positive supply voltage used by the load is not connected to the plug. A pulldown resistor is used to keep the MOSFETs switched off when the I/O pins are not connected, or not set up as outputs. Also, keep in mind that this plug ties the plug signal ground and the load ground together – it is not isolated from the load power supply.
The length of the plugs is 34 mm, making them a perfect fit for the Carrier Board + Box:
Note that a closed box provides little airflow to cool the MOSFETs, so this setup is not recommended for high-current use. Having said that, I’ve been driving a few meters of RGB LEDs with these MOSFETs without them even getting warm. See this earlier weblog post.
For dimmer use, there’s example code for a remote-controlled JN and 4 MOSFETs using software PWM.
A Murphy-less plug, so to speak :)