Rockets and Rayguns radio

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This was a prop for the Rockets and Rayguns Larp game. It is supposed to be the 1950s radio used in the base. Its basically a fancy walkie-talkie conversion with a pair of BaoFeng BF-888S. (Actually conversion is the wrong word, i managed to get away without having to open the walkie talkies themselves)

This is the finished radio. As you will see later, Some bits do something some don't. It was intended that they all do, and if the prop gets used again, more of it will. The build was done around a Baofeng BF-888S, which is a reasonably regarded for the price walkie talkie. The clock section down the bottom is separate. it was mainly put in because i had a big space at the bottom of the case, and i had the electronics around already from last years rockets and rayguns timer project.

The box is in two parts. Most of the electronics are mounted to the lid. The batteries are in their own shelf in the box itself. The batteries are three 5Ah 12v Sealed Lead acid batteries from am old UPS. These should give a total run time for the items they power of about 60 hours, which should more or less match the Walkie talkie batteries. This was important because the radio still has its separate battery, so I needed two separate chargers. Therefore i didn't want to have to charge it at the event if at all possible. The 12v supply powers the 10w audio amp as well as the Arduino and Nixie tube drivers. These take a total of 200mA constant current. Note that this is separately switched from the radio as this still uses its 3.3v internal battery. This has a life of around 3 days depending on the usage. Both proved adequate for the task.

The arduino was originally going to control a lot more, including indicators for RX and TX (I was going to tap these from inside the radios, but once i got it apart, i realised i would damage them if i tried that.) The far left and right meters are actually connected to the 12v power supply and the 3.3v power supplies, so do serve a purpose. the two middle ones are not connected.

You can see the high voltage inverter for the nixie tubes mounted in the lower middle. I did actually build one of these for last year's project, but it was unreliable. (If you went to last years R&R you may remember they flickered a lot occasionally. This wasn't deliberate!) I think when i was building it i ordered the wrong inductor size, and it was crowbaring the output, resulting in lots of current being drawn but low output voltage. I found this pre-made one on ebay for a fiver, so used that instead.

The amplifier board is a 10w cheap Chinese jobby. I was going to make one, but when i saw the price, i decided why bother... The arduino board is a cheap Chinese version, which was also dirt cheap, the RTC was pennies. and the custom nixie boards were from last years R&R project.

This is the radio arrangement. The radio is in the charging base. Note, the attachment of the switch connections to the radio. one side goes to the chassis mount, and the other do the pin under the little purple piece of paper. The relay is there because of a problem with the charger. It seems if you leave the charger unplugged, it DISCHARGES the battery. in about 3 hours. This is not ideal. The relay is triggered from the mains input and disconnects the battery from the charging circuit when its off. Also, you can see the breakout board from the headphone sockets, which allows easy access to the txrx/mic and speaker pins.

This is the radio. I didnt actually do much conversion for this as such. All i needed out of it was: tx/rx switch, Audio output, Power switch, and microphone. Most of these are provided by the jacks, other than the power switch, and this was hacked using a piece of thin plastic to isolate the ground from the pin on the radio, and taking a tap from the battery and the Radio Chassis.

To be able to interrupt the power, i simply wrapped a piece of wire around the negative pin on the battery, then inserted the battery with a thin piece of plastic to prevent the pin contacting the tab on the radio itself. As can be seen, the ground plane is the chassis. This meant i could control the power to the radio with a simple switch between the wire and one of the metal bits of chassis that are sticking out to attach the belt clip.