The inventor tried to design a power system for it but he has absolutely no experience with electronic design. Right now he has three different sources, 18V (aka two 9 volts in series) for the RF relay board, one 9V for the 555 circuit, and two AAA for the electronic whistle. It also has four more 9Vs, one for each LED!!! Each LED board is its own circuit. One 9V is connected to the LED and the circuit is switched on by one of the relays from the RF board. this right here is one area I provide a major improvement for.
So a big redesign is needed. I took a look at the data sheets for all the different modules. The RF relay board needs 12-24 volts. The mono stable latch needs 9-12 volts according to the sheet, but looking further into the design, I'm pretty sure I could go higher if I needed to. 555 timers can usually go up to 15V no problem. The LED boards need 8-30V. So for all those modules I can use a 12V supply, maybe more but I will look at that during testing. I'm not sure what the whistle needs, it runs off of two 1.5V AAA cells. It has an epoxy blob over a chip-on-board so I can't really tell if it can run any higher. I'll do another post on my attempts to reverse engineer the whistle. To be safe I'm just going to use a 3V supply for the whistle.
The other requirement for the design is that it needs to be rechargeable Basically, the users were getting tired of replacing the alkaline batteries. Even if they were to get rechargeable 9Vs, there are too many of them anyways. So my design needs to use a single, rechargeable pack. After looking at the voltage requirements, I should be able to use two supply rails. One 12V and the other 3V.
My first thought was to use a couple of linear regulators but the efficiency with those is just crap. I would need a heat sink or two if I was going to use those. And that would take up far too much space. So I decided to start looking into buck converters. When I first started looking, I figured I would have to design a circuit based off the application notes in a data sheet some where, design a PCB and get prototypes made. All fun and stuff but that takes a lot of time.
Luckily, once I started searching for parts, I ran across a very cheap module that can be found for as low as $0.99 on eBay Basically its the circuit directly off the LM2596 data sheet. Input is 3V-40V DC and output is 1.5V-35V DC. The input must be 1.5 above the output and it can provide up to 3A. So I ordered a couple of of amazon in order to get them faster than buying them of eBay as the supplier was in China.
Now all I have to do is get a rechargable battery that can provide 13.5V or more and use the buck converters to bring the voltage down to 12V and 3V. I think one of the Turnigy 4 cell batteries used in the RC world could be used for this no problem.
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