Modify 25mW SPMVA2500 for 1S operation

If you have not heard about the tiny whoop yet, then you have to come out from your bunker 🙂 This summer’s hottest item is the so called “Tiny Whoop”. This is in reality nothing else, just a beefed up “Inductrix” from Horizon Hobby. I already prepared a little article about the Inductrix, click here to read it.

This article however will describe how to use a better – 25mW transmitter/camera combo on the tiny whoop/inductrix. The SMPVA1000 from horizon hobby is a 5mW only transmitter which will work well without modification on the Tiny Whoop, but it will give you limited FPV satisfaction because the 5mW transmission power only. To increase the range and signal clarity, you need to use at least 25mW (SPMVA2500), which is available, however it was designed to be powered from a 5V power supply. This originally was designed to be powered from a minimum 4.8V power line by being plugged into an RC Receiver. If it is, you can even change the video channel through a PPM link.

Let’s take a look at the SPMVA2500 and what do we need to make this work from 1S (3.7V) battery. When you open the box, the 25 mW transmitter/camera combo looks like this:

25mW TX and CameraAs you can see, there is a servo cable sticking out from it, this can be powered from an RC receiver. We will show you how to modify this without actually removing the original cable. YOu can remove it on yours if you will only use it for the Tiny Whoop that way you will save a few grams of weight. So let’s see what you need to make this happen:

  • – one SPMVA2500 25mW TX and camera combo, you can get it from here: http://www.nghobbies.com/cart/index.php?main_page=product_info&cPath=1_50&products_id=1591
  • – a small exacto knife or hobby cutter with blade no. 11
  • – fine tip soldering iron with temperature control
  • – needle nose tweezers
  • – a good magnifying glass, or good eyes 🙂
  • – solder wire
  • – some 28 gauge red and black servo wire
  • – 47uH micro choke to eliminate the interference coming from the motors

Once all these are in place go ahead and follow the steps below:

  1. Carefully remove the casing from the camera, this will save you a bit of weight.

To remove the camera plastic housing, you can use a small screw driver to push out the back plate as per the images below. Once the back plate is out, slide the camera out from the casing, be mindful of the little button on the top, be careful not to break that off:

2. Identify the pins you will need to solder your 1S battery leads to. Two pictures below should clearly identify which are the pins you will need to solder your 1 cell battery wires to. The GND stands for Ground and this should have your Black or negative connection and the 3.7V is the positive, this is where your battery positive line would go. Now, if you would only solder it on directly, you will get quite a bit of noise and interference when throttleing up. The interference comes from the brushed motors and it can ne eliminated using a small 47uH choke on the positive line.

The part number for the tiny choke to be used in this project is: 445-1964-1-ND and you can get this from www.digikey.com or www.digikey.ca if you are in Canada:

Tiny choke

3. The hardest part is to solder the choke to the connector on the PCB. You need a steady hand, good eyes and an even better soldering iron to achieve this. I personally used a microscope, so that made my life a lot easier, the following pictures were taken through the viewfinder of the microscope:

You can click on each individual image above to see the magnified version.

4. As you can see in the above images, you have to be brave to attempt this soldering job 🙂 After you installed the choke, now you can install the black and the red wires, these will be later soldered directly to where the battery leads are soldered into the Tiny Whoop controller board:

3.7V power cables soldered in

If you accomplished all this, congratulation, you have great soldering skills, now go ahead and help others out as well 🙂 All what is left, to solder the other end of the black and red wires to the battery leads on the Tiny Whoop.

With this installation we bypassed the main voltage regulator on the SPMVA2500. Since the main filtering on a power supply is happening before the voltage entering the voltage regulator, the out line is filtered only barely. For this reason  we need to add the above mentioned choke to filter out all the incoming interferences from the motors.

Amazing power and extended flight time can be achieved if the new 200mA 1S LiPo battery is used in conjunction with the Tiny Whoop. You can order it by clicking on the picture below:

200mA 1S Tiny Whoop Battery

I hope you find this article helpful.