How to offer job for board and LED design?

Hi Brian,

One thing you might try is simply replacing the LEDs on the cards you have with brighter devices. Any LED with a brightness rating over 1000 millicandellas will be visible in direct sunlight - obviously most automotive LEDs work in sunlight. It will not hurt the circuit to have brighter LEDs installed, assuming they are the same color. You may need to install a switch to reduce brightness at night or add a slightly more complex circuit to automatically dim in low ambient light.

If you want to have a module built, you probably don't need a microcontroller like an arduino.

For example a single chip like an LM3914 can convert an analog voltage or pot output into a 10 LED bargraph. The schematic in the datasheet may be adequate for your application.

A little ,more info would be useful in optimizing he design

- how big should the PCB be?

- how may LEDs?

- what color?

- what signal controls the number of LEDs?

etc.

Doug

These boards cost me $70 each which is WAY to expensive for what I need. Replacing these LEDs would seem to be a poor investment.

Pictures attached. The board is 2.5" x 1.75" the 1.75" is perfect for this case and would be most convenient to stay equal or less than that.

There are 20 LEDs on this board 4 of which always stay on. 10 LEDs would be plenty if only the first one stayed on. Red LEDs are perfect but I'm not really hung up on the color.

These are point of purchase displays for dealerships. I am going to have a digital picture frame behind the display so I ideally the board would be able to share the power supply from the picture frame. the one in the picture uses a 5V___1000ma supply so 5V would be ideal, however I can try to find something else.

I'm not stuck on the Arduino, but definitely need something better than what I have now.

Just kidding on the pictures. I am going to have to retake them or scale them way down to upload here.

Hi Brian, it looks like you've got the bar graph chip Doug mentioned. If it is to go on a bike then I'd swap out those sockets and solder the chips directly but if it's to be office based then that's not an issue.

To be honest $70 for a a small batch of boards is not a bad price. You will find that the costs are not due to the selection / number of components but the design and assembly time. If you have thousands to make then you should be able to get the unit cost down. I'd have thought you could swap the LED array out with high brightness LEDs, either thru hole or surface mounted to solve the light problem and reduce the part costs. If you can't change the board then you could have a daughter board built with the same pin out as those LED arrays that could be swapped in.

The key reason to swap to a micro-controller would be if you want to experiment with different algorithms for converting the movement to lights on.

Could you do this with a nano, possibly, alternatively a Pro Mini or similar to get a few extra pins. You might need to use transistors to drive the LEDs, the ULN2003 is cheap and commonly available. You don't actually need a whole Arduino board to do this simply start with an ATMEGA328-PU chip. However, once you start making custom PCBs and putting a few other components on and you'll likely find yourself back in the $70 mark.

Hi Brian, it looks like you've got the bar graph chip Doug mentioned. If it is to go on a bike then I'd swap out those sockets and solder the chips directly but if it's to be office based then that's not an issue.

To be honest $70 for a a small batch of boards is not a bad price. You will find that the costs are not due to the selection / number of components but the design and assembly time. If you have thousands to make then you should be able to get the unit cost down. I'd have thought you could swap the LED array out with high brightness LEDs, either thru hole or surface mounted to solve the light problem and reduce the part costs. If you can't change the board then you could have a daughter board built with the same pin out as those LED arrays that could be swapped in.

The key reason to swap to a micro-controller would be if you want to experiment with different algorithms for converting the movement to lights on.

Could you do this with a nano, possibly, alternatively a Pro Mini or similar to get a few extra pins. You might need to use transistors to drive the LEDs, the ULN2003 is cheap and commonly available. You don't actually need a whole Arduino board to do this simply start with an ATMEGA328-PU chip. However, once you start making custom PCBs and putting a few other components on and you'll likely find yourself back in the $70 mark.