Step-up converters (or boost-converters, although I like the first title because in my mind it more accurately describes its function), create a higher DC output voltage from a DC input voltage.

In my case, I'd like to have 12V output, at 1.2 W, which translates to 100 mA output current. More is welcome, but only if it's a cheaper module.

Oh, and I probably am going to use a solar rechargable battery pack, which puts out 5VDC.

Let's have a look at a step-up converter that fits the bill.

I'll put my comments in cursive.

This looks like a nicely layed out board. Plenty of space between components, each component has got a reference designator (R103 etc), although not very clearly, and the input pins are labelled, power traces are made thicker than others, so this is put together with at least some care. That's a comforting thought.

Description:

Input voltage 3 ~ 6V, output 12V (deviation +-5%)

Okay, nice low starting voltage, and we can use 5V.

Maximum input current: 1.5A

That's a bit odd because they only mention 1A further below. But that's fine.

Long-term work Current： 1A.

Much more than we need. Good.

Conversion efficiency : 90%

Very good, I've seen far worse (especially for chinese dev boards)

PCB size : 25MM x 15MM

Start Voltage 2.8V, Output Current 50MA

INPUT 3V 1A; OUTPUT 12V 220MA

Okay this is already more than we need for one of our three motors, and we're not going to drive them all together, I imagine.

INPUT 5V 1A; OUTPUT 12V 370MA

Fine, this can drive 3 of our motors simultaneously.

INPUT 6V 1A; OUTPUT 12V 450MA

This is with on/off switch voltage boost module.The master chip is FP6291GLR,for more Details,click here!

That would've been nice if click here were actually a link, which it wasn't. I've managed to find it here. It's a step up convertor indeed, with a power down current of 0.1 uA, which is good for our purposes. Also, it has adjustable overcurrent of 0.5-2.5A, which is good for us too, if we set this to 0.5A it will limit motor dissipation to 6W, and possibly protect the gears if one of the threads jams.

Can used the input voltage (VIN or GND)control the switches,also use MCU IO control the switches.

This means that we can control the functionality (enable) with a voltage anywhere upto VIN. In reality the minimum enable voltage is 0.96 VDC, which indeed is something most MCUs can do.

Control current is very small, MCU IO port can be directly controlled. Including micro-controller : ARDUINO UNO MEGA2560 AVR STM32 ARM PIC AT89C51 STC MSP430 FPGA CPLD etc.

This is info for noobs.We're above that, surely?

When the EN pin = GND（OR MCU LOW level),the boost module is working properly;

When the EN pin = VIN(or MCU HIGH level,3.3V/5V) OR Not Connected(or MCU High impedance), the boost module into standby mode, stops working, the output voltage is 0V (Can measure the output voltage is 500~800MV, which is inductive output voltage, you does not have to bother).

Okay, I'm glad we does not have to bother. I'm not sure with what we don't have to bother with? In any case: what is meant here is that the module is enabled if it's pulled to ground, otherwise it's in standby. That's fine, we can just use a simple NPN transistor to pull this pin to gnd. Also, and this is important, it looks like when the module is disabled, it cuts out the output voltage to 0.5-0.8 MV (do they mean 0.5-0.8 V???). In any case, some step-up converters just pass on the input voltage directly to the output when the module is disabled, in that case our motors may still be powered. So it's all good.

Applications：

1.Battery powered equipment, 2.Wirels mouse, Wireless keyboard 3.Toys 4.Camera, Video camera 5.VCR 6.PDA 7.LED Lighting 8.Wireless communication equipment 9.MP3/MP4 player 10.Audio equipment

Well they have a very large imagination. Who wouldn't want to power their wirels mouse? They should include "solar powered heliostat". Perhaps I should email them.

Package listing:

2 PCS 5W With ON/OFF EN Switch DC3-6V To 12V Step-up Boost Converter Power Module

These modules will do the trick, in fact, I only need one of them, the other one will be put in the spare parts drawer.

Now we need an H-bridge for the motor.