Engineer to complete designs and solve some power problems

This project was awarded to Davelelievre for $200 USD.

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Project Budget
$30 - $250 USD
Total Bids
Project Description

I have a schematic that needs an electrical engineer's expert knowledge for a few hours. The project is a portable display with 4 7-segment characters built using the Arduino, some BCD-7 Segment Latches, and some Darlington transistors to supply the segments. Each segment is composed of multiple LEDs. I would like to take my prototype to production, but there are a few issues to resolve first. These are the issues I have with my current schematic:

1) After a few hours of operation, the LEDs get dimmer and dimmer. I believe this may be a voltage regulation issue and the LEDs are attempting to draw too much current, heating up the regulator and reducing the voltage, but I do not know for sure and don't know how to resolve the problem.

2) When plugged in to the wall outlet (instead of 8 AA batteries), the IR remote control receiver will not work. I believe this may also be a voltage regulation issue. I tried using an additional voltage regulator and some capacitors to smooth out the supply voltage to the just the receiver but that had no effect. I have also noticed that the speaker buzzes ever so slightly when this is happening.

3) When the brightness is turned down on the LEDs (using PWM to blank the LEDs rapidly), the remote control receiver stops working even when battery powered. My first thought was that it was a timer issue on the microcontroller, but the documentation tells me no. Maybe the switching current draw by the LEDs is making the lines noisy.

The winning bidder will look at my schematic and offer advice and modifications to it to resolve the three issues. Additionally, the bidder should have ample knowledge of taking a design to production and will offer advice and modifications to the schematic to make the design robust and capable of meeting common design practices. I would like to know the optimum supply voltage to power the LEDs and have the proper voltage regulation to ensure that they work correctly, and I want to be confident that this design will work for years without damaging the components.

If you require the schematic or current BOM or additional details in order to estimate the bid, please ask.

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