NEW PRODUCT – ULN2803: 8 Channel Darlington Driver (Solenoid/Unipolar Stepper) [ULN2803A]. Bring in some muscle to your output pins with 8 mighty Darlingtons! This DIP chip contains 8 drivers that can sink 500mA from a 50V supply and has kickback diodes included inside for driving coils. This will let your little microcontroller or microcomputer power solenoids, DC motors (in one direction) and unipolar stepper motors.
Please note, this is an ‘open collector’ driver – it can only be used to connect the load to ground and there will be a 1 Volt (or more) ‘drop’ across the internal transistors. The inputs can be driven by 3.3V or 5V logic. Fits nicely in any breadboard or perfboard.
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Is this avalible in a shield for an arduino? Put this in line with an 8 wide DIP switches (or maybe a 16 or 13 pin – so it can be selectivly interfaced with any arduino pin, at some risk of a person flipping the wrong switches) so that it can be disconnected on certain pins and it instantly becomes compatible with almost any arduino shield. Days like this I wish I had a PCB mill…
@Andrew, I put a uln2803 on a protoshield together with a mcp23008 and a couple of connection terminals. I use it to drive relays. Works great and saves a lot of Pins!
BTW, I’ve been wondering if you can turn something like this into an H-bridge by adding just a simple resistor and PNP transistor to the high-side. http://www.flickr.com/photos/58843278@N00/7847799300/
This has potential frugality advantages since low-side drivers are pretty common and cheap, and pnp transistors are cheap, but high-side drivers or full h-bridges are rarer and dearer.
The demands on the PNP transistor (for gain/etc) are pretty low, since the ULN can provide a lot of base current, and does the voltage conversion…
Is this avalible in a shield for an arduino? Put this in line with an 8 wide DIP switches (or maybe a 16 or 13 pin – so it can be selectivly interfaced with any arduino pin, at some risk of a person flipping the wrong switches) so that it can be disconnected on certain pins and it instantly becomes compatible with almost any arduino shield. Days like this I wish I had a PCB mill…
@andrew, not yet – but stay tuned!
@Andrew, I put a uln2803 on a protoshield together with a mcp23008 and a couple of connection terminals. I use it to drive relays. Works great and saves a lot of Pins!
BTW, I’ve been wondering if you can turn something like this into an H-bridge by adding just a simple resistor and PNP transistor to the high-side.
http://www.flickr.com/photos/58843278@N00/7847799300/
This has potential frugality advantages since low-side drivers are pretty common and cheap, and pnp transistors are cheap, but high-side drivers or full h-bridges are rarer and dearer.
The demands on the PNP transistor (for gain/etc) are pretty low, since the ULN can provide a lot of base current, and does the voltage conversion…