The Project TouCans Power System

Project TouCans has been flying with its power source onboard for several months. It occurred to me I've never documented the power system in its entirety.

The Battery

The foundation of the power system is an Imuto potable laptop charger

Using this charger as a power supply for TouCans has two advantages. First, it fits in a Progresso soup can, so it fits the form factor of the rig that's more often than not flying suspended in its own dipole antenna. Second, it has two USB-C ports. One is attached directly to a USB-C power deliver breakout board that then feeds the the latching relay that serves as the on/off switch for the rig's radio and amplifier. The other USB-C port sports a short USB-C thunderbolt cable protrudes from the can and allows the battery to be charged without opening TouCan's case.

Choosing the Voltage

So, we have a supply that provide up to 100 Watts. But at what voltage? That's what this gadget, an Adafruit HUSB238, determines.

It's jumpered via a solder bridge for 15 Volts going into both the RockMite and the Tuna Topper II amplifier.

If the power source can't provide the voltage requested by the jumpers, then the default output is five volts. The Imuto supply does fine with a selection of 15 volts at 2 amps.

Here are the available downloads for the board.

Sadly, the board can't be programmed to simply not supply power at all. That's where the next step of the system comes in.

The Latching Relay

To cut off both power leads without constantly pulling coil current, TouCans uses one of these

Datasheets have been hard to find for this Amazon purchase, (sold out at the time of this writing), but there's a video on how to use the relay. I wrote a number of posts about this relay while KO6BTY and I were learning how to get it to work.

https://copaseticflow.blogspot.com/2024/10/labbook-project-toucans-onoff-relay.html

https://copaseticflow.blogspot.com/2024/09/labbook-project-toucans-onoff-relay-bit.html

https://copaseticflow.blogspot.com/2024/09/labbook-project-toucans-power-and-keyer.html

This relay along with the keyer relay consumes more current thatn the Pico-W is willing to provide from its GPIO pins, so we use a Darlington transistor array to switch a 4.5 Volt set of AA batteries, (the same ones that serve as the supply to the Pico-W), directly to and away from the relay.

The Raspberry Pi Pico-W That Controls it All

We turn the rig on and off via the WiFi connection to Project TouCans. We arrived at this design decision because at least half the time the rig is suspened twenty feet above us in its dipole. The Pico-W also controls the keyer and is housed outside the rig to reduce RFI issues and to not isolate the onboard WiFi antenna from the rest of the world behind the pineapple can that serves as the rig's main housing. You can see the arrangement below.

It has a shroud of black electrical tape around its pins and is lifted away from the rigs case via a roll of electrical tape, (again to reduce RFI from the Pico-W itself.) In this picture, we're using TouCans in vertical antenna mode.

And that's it! That's the ToucCans power system from top to bottom and off to the side. The battery is housed in the lowest can in the picture above. The small black battery case holds the 3 AA batteries for the Pico-W and the relay coils. The board shown below containing the Darlington array, the latching relay, and the keyer relay, is nested inside the Pineapple can the Pico-W is hovering over.

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