Power Supply - Piscean Works

Choosing a power supply for your circuit is easy. There is no rule of thumb or guide on what is the best option. However, do consider the following points when you need to design your own system, be it for home display or in a modeling competition.

Things get complicated when you need to decide whether your model needs to be displayed at home or to be brought out. Anyway, the table below are my tested theories and some being verified during shows.

Solution	12volts	9volts	5volts	Pros	Cons
No. of AA, AAA, C, D equivalent, etc.	8x (1.5v) = 12v	6x (1.5v) = 9v, or one 9v battery	3x (1.5v) = 4.5v	-When there are no power points -Available in all countries	-You’d need to get a lot of them
PC PSU	YES	Voltage Converter	Voltage Converter	-Pumps out a lot of current -Can power a LOT of models	-No reverse voltage protection -Build your own Safety cut-off switch and terminal connectors -Make sure it can switch between 110VAC and 230VAC -Limited to 5volts and 12 volts
Wall Adaptor	Voltage Selector Version	Voltage Selector Version	Voltage Selector Version	-You can select the working voltage	-Do label the voltage selected and also, the polarity option
12V Wet Cell	Yes	Voltage Converter	Voltage Converter	-Hey, it’s 12 volts!	-Needs charging -Bulky & heavy -Do not short the terminals
9V battery	Voltage Booster	YES	Voltage Converter	-Why?	-Require multiple units depending on model requirement
Mobile Bank	Voltage Booster	Voltage Booster	YES	-Slim and light	-Actual capacity might vary, depending on manufacturer -Slim packs might be of lower capacity or using Li-Po -Lipo packs will expand over time -Requires minimum current, otherwise shuts off in 30 seconds
Li-Ion, Li-Po	Yes, with Voltage Converters	Yes, with Voltage Converters	Yes, with Voltage Converters	-Build your own with casings and circuits	-Capacity depends on budget -Some designs might require spot welding -Might catch fire -Might have a minimal current drawn requirement or it will auto shut off

VOLTAGE CONVERTERS

In some cases, you will need to step the voltage down (buck) or boost it up. These DC-DC Voltage Converter modules are very convenient. In a pinch, you can use these voltage converter modules to solve your voltage issues. But do read on their technical specs or features to see if this is what you need. Some of these modules do look similar but they do have different functions.

DC-DC BUCK CONVERTER (STEP-DOWN)

DC-DC BOOST CONVERTER (STEP UP)

This is the bigger version which has a LED display for the input and output voltages. Because of that feature, you can use it to calibrate the other converter modules shown above, especially when the they have a load (your circuit). In a sense, I am using this as a Digital Voltage Meter. But look closer in the video, as there are other voltage meters being used too. But if you need accurate reading, I suppose a very good (Fluke?) Digital Multi-meter would be the best solution.

Once you have your modules prepared and calibrated, do label them on their functions, voltage ins and outs. Because you might have a few on hand and it is so easy to mix them all up.

I use this DC-DC step down module (right) to quickly calibrate the boost module on the left. This is the fastest way but whether the voltage meter of the module itself is calibrated, that is another question. If in doubt, get at least two to three modules and get their average reading if you do not have a Digital Multi-meter handy. Ha ha.
By pressing the small button, it is reading the input voltage (signified by the red LED), and so, I used a screwdriver on the boost module until I get a 12v input But I am not sure if the left module would output a lover voltage if the actual load is great.

With the boost module (left) giving me 12volts, I now step down the voltage on the output (signified by the green LED) to 5volts. I do not need to do this step unless I really have a power source I need to step down to.

Some last minute thoughts while I’m doing this page (It’ll be relocated later)

THE WONDERFUL 5 VOLTS

Maybe I need to call this the Universal voltage. You can get 5v from a computer power supply, a USB mobile phone charger (but never from the computer’s USB ports, please) and all microchips uses them. For this reason, I designed my circuits to use between 4.5v to 5v. I can get the former from just 3x AA or AAA batteries while the latter can be from the mobile phones or any specialised battery case. During a show, I let it run for the day and charge the packs overnight. The only difference with the above category is that these solutions are lighter and comes in a slim package.

However, there is a problem with mobile phone chargers nowadays. These intelligent chargers would only stay on if it detects a significant current draw. Sadly, most of my circuits would be ignored by these newer units as the power consumption is too low.

INSIDE THE MODEL

If possible, I would like to put all the electronics inside the model. The main reason is that I do not have to worry about wiring issues if I have a lot of LED points in the model. This way, I can minimise the number of wires going into the model, which is just a pair, mainly for power. However, most of the time, you would be looking for nooks and crannies to get the PCB in. For me, in some cases, I would need to create a new bespoke PCB if my usual goto generic PCBs are still too big.

OUTSIDE THE MODEL

Assuming there is not enough space inside the mode, or there were minimal lights, you can put the circuit board outside of the model. The only disadvantage is that you would need to take into consideration the amount of wires going into the model for each LED. The good thing is, this method allows you to troubleshoot your circuit or tweak its timing/sequence and even repair. However, if the model was to be placed in a stand, you would need to make sure the stand can accommodate the wiring. I suppose this would be ideal for dioramas as everything is ‘fixed’ to tell a story.

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