Drone kit – ZMR250 PDBs


In my job lot of ZMR 250 frames that I obtained from eBay, two of the popular, but basic, Diatone PDBs were included, one was version 2.1 and the other version 2.2, as well as an excellent RCTech v4.1 ZMR250 PDB. I’m not entirely sure what the difference is between version 2.1 and 2.2 of the Diatone PDBs, as yet. The RCTech PDB allows for on-board placement of a Naze32 flightcontroller and a Micro MinimOSB.

This, then, led me on to a brief voyage of discovery with respect to ZMR250 specific PDBs.

See also Drone kit -ZMR 250 and PDB.

The featured image above is of the Diatone PDB for ZMR250 (SKU224435) [Source 12, and 3)


A Power Distribution Board (PDB) is a useful item, which is basically a Printed Circuit Board (PCB) that can distribute power to the Electronic Speed COntrollers, or ESCs. More complex PDBs can also distribute power to other components, such as LEDs, FPV cameras, as well as signals from flight controllers. These more complex types can also be integrated into the drone’s main body plate. PDBs will also have a maximum current rating, so be sure to choose one that matches firstly the maximum combined current drawn by your ESCs, and secondly, the combined current drawn by your other peripherals.

These PDBs are specific for the ZMR250/QAV250, and are shaped the same as the quadcopter and are designed to replace the middle, or bottom, plate.



There are a large number of manufacturers, including:

  • Diatone
  • Overcraft
  • Nucleus
  • Unmanned tech ZMR250 PDB V2.1, £15.99
  • Cytryna
  • OSO
  • RCTech

Diatone versions

Version 1 was superior to the initial version 2.1, which was slated universally. Version 2 has slotted holes for the arms, whereas version 1 only has round holes. According to the thread, the slotted holes are not so good for the arms in the event of a crash:

I don’t like the slotted holes for the motor arms. In a crash the slots will not hold the arm screws, making it possible for them to move and break out the opposing frame plate around the screw holes. Impact on the ends of the arms, the most common type of crash strike, has a great deal of leverage against that relatively small bolt pattern. I have sheared steel bolts in some particularly hard crashes!

This thread, Diatone Power Distribution Board for ZMR250/H250 : Entirely Too Good For The Price!!! has a very in-depth dissection of the version 1 PDB.

RCTech ZMR v4.1

From ZMR250 PDB v4.1 – Power Distribution Board. German PDF (link) from RCTech

ZMR250 PCB v4.1

with 5v / 12v BEC, LC filters, buzzer and LEDs.


  • Designed for Naze32, F3 and the CC3D
  • To avoid LC filter disorders FPV transmission
  • Flight Controller: Naze32 / CC3D + 36 x 36 mm (30.50 x 30.50 mm mounting hole)
  • LED Voltage: 3S – 4S Li-Po
  • 4 blue LEDs front
  • 4 red LEDs behind
  • Buzzer
  • Weight: 33g
RCTech ZMR250 PDB version 4q
RCTech ZMR250 PDB version 4

Flying Tech

The Flying Tech ZMR 250 PDB with Naze32 Acro & MinimOSD, £40, and ZMR 250 PDB with Naze32 Full & MinimOSD, £50 are similar boards to the RCTech PDB, but not exactly the same. However, as with the RCTech PDB, they can take on-board Micro MinimOSD and Naze32 boards.

Flying Tech ZMR250 PDB instructions

With Naze32 Acro:

Flying Tech Naze32 Acro PDB
Flying Tech Naze32 Acro PDB

With Naze32 Full:

Flying Tech Naze32 Full PDB
Flying Tech Naze32 Full PDB

Placement of Micro MinimOSD – the orange squares use right angle header pins, the blue squares use straight header pins:

Flying Tech ZMR-OSD
Flying Tech ZMR-OSD

Similar boards

ZMR250 PDB w/ LEDs & Buzzer (Integrated Power Distribution Board for Clean build), $29.99

  •  Version 2 of the ZMR250 PDB now supports both CC3D & Naze32 Flight controllers. Please set the Orientation in configuration software after installing and programing the flight controller
  • Battery connections pads. Supports upto 4S LiPo battery
  • FPV Camera and Video Transmitter connection pads. Both has LC Filter to smooth DC power. (Use 12V step down voltage regulator provided)
  • Loud Buzzer (un-assembled, solder yourself) for CC3D you will need PWM buzzer, this will only work with Naze32
  • Micro OSD solder pads (Need Micro OSD ?? Get it HERE >>> http://www.ebay.com/itm/181842238759)
  • Bright two color LEDs for orientation
  • LC Filter to provide smooth DC voltage to FPV camera and Video transmitter both
  • Flight Controller mounting hardware included
  • Extra Header pins are included

PDB PCB Power Distribution Board BEC Filter Buzzer LED QAV250 ZMR250 CC3D RC289, £9.29, comes with these accessories:

RCTech PDB Accessories
RCTech PDB Accessories

Excellent and structure fit to match the QAV250 ZMR250 frame (not suited for EMAX 250 frame kit).
Suit for CC3D, Naze32, SP Racing F3, MINI OSD flight controller.
Bright LEDs for orientation and Loud Buzzer (un-assembled, solder it yourself).
LC Filter to provide smooth DC voltage for FPV camera.
Flight controller mounting hardware and extra header pins are included.
Battery connections joint, FPV camera and video transmitter connection joint.

Color: black
Dimensions: about 184 x 68 x 7mm/7.2″ x 2.8″ x 0.3″

BEC no welding, please be careful when you weld to prevent short circuit.

Package includes:
1 x Power distribution board
1 x User manual
1 x Set of accessories


A buzzer is required for the above RCTech PDB, and clones. As stated above the buzzer needs to be PWM for CC3D flight controller. This is, however, a bit of a confusing, and misleading, statement. By PWM, they presumably mean a passive speaker is required for a CC3D flight controller, and that an active buzzer is required for Naze32. However, see Buzzer does not work, which states that, for CC3D,

You must have an active beeper, with a transistor buffer stage.

See also github: cleanflight/docs/Buzzer.md – Types of buzzer supported:

The buzzers are enabled/disabled by simply enabling or disabling a GPIO output pin on the board. This means the buzzer must be able to generate its own tone simply by having power applied to it.

Buzzers that need an analog or PWM signal do not work and will make clicking noises or no sound at all.

Examples of a known-working buzzers.

Also from github: cleanflight/docs/Buzzer.md – Connections/CC3D, See the CC3D – buzzer circuit.pdf for details:

Buzzer circuit for CC3D
Buzzer circuit for CC3D

See also Active vs Passive Buzzer:

An active buzzer will generate a tone using an internal oscillator, so all that is needed is a DC voltage. A passive buzzer requires an AC signal to make a sound.

Confused? Does active mean that there is a transistor buffer stage, or an on board oscillator? It all stems from the fact that the term active is somewhat ambiguous. There is the, in electronic terminology, active, which has the transistor buffer stage, for amplification, and then there is, what could be termed as, “active active”, which has the on board oscillator.

The CC3D will output a steady state signal, that is to say that the line is bought HIGH -not an oscillating signal – and so it requires a buzzer with an on board oscillator. From $ 129.99 Eachine Racer 250 FPV Drone Built in 5.8G Transmitter OSD With HD Camera:

This buzzer is called active because it is driven by a transistor but it doesn’t resonate on it’s own and needs to be fed with a frequency. The CC3D will only switch a signal on and off thus you need an “active active” buzzer with transistor driver AND build in resonator.

In this case “constant” is a steady voltage in the duration of the beep.
I think it was FyreSG who tested one of those “active passive” buzzers and just got it clicking on the transinients.

Buzzer dimensions:

  • Pin pitch:  5-6 mm
  • Width: 9 mm

There are a couple of buzzers that can fit. Firstly, the 5.5 mm (7.5 gramme) buzzer 200pcs/lot Active magnetic buzzer 1.5v 3 v 5v 9v 12v 9 * 5.5 (9 mm * 5.5 mm)

Buzzer dimensions
Buzzer dimensions

Secondly, the 4.2 mm (6 gramme) ultrathin buzzer, 200pcs/lot 3v 5v 12 v ultrathin active electromagnetic buzzer 9 * 4.2 (9 mm * 4.2 mm)

Ultrathin buzzer dimensions
Ultrathin buzzer dimensions

Unmanned Tech

ZMR250 PDB V2.1

Product Description

This is a custom power distribution board (PDB) for the ZMR250 quadcopter. This is an awesome PDB as it has plenty of features that makes building your ZMR250 quadcopter a breeze. This PDB also neatens everything up very nicely and saves on space and weight.

There are in-built ports for all four ESCs on the PBD (as you can see in the pictures) as well as a LC-filter for your FPV gear, a lost model alarm and mounting holes to incorporate a battery monitor alarm. This PDB also has plugs to plug in a balance lead to power your FPV gear. Thanks to the design of this board, this power supply is first fed through the LC-filter before it reaches your FPV gear, thereby smoothing out the signal.

This pack also comes with a 3S and 4S balance lead, an XT60 connector cable and others.


Usage of a Diatone PDB

The procedure is documented in Diatone PDB – How to wire.

NOTE: About drilling – it is not recommended:

You have drilled through the ground planes of the PDB on the both sides.  A substantial part of the PDB’s underside is also a positive layer.  If you drill a hole through both and use a conductive bolt you’re asking for trouble.

And just because you don’t see traces doesn’t mean there aren’t any.  PCBs can have multiple layers between the top and bottom (think power lines behind a wall).  I’d strongly advise drilling holes into them unless you know for sure that you won’t touch and planes or traces.



**** Do at your own risk, I will not take responsibility for any damage caused****

Here are my instructions to wire up the Diatone PDB from BangGood – Costs £3.81* (as of 24/06/2015).

It does not fit the ZMR250 frame BangGood offer apparently, so you’ll have to measure up.


What you’ll need:

Soldering Iron + solder
Wire cutters
Drill with 3 mm bit*

( If you want your FC on the board and to have the PDB as the centre board. Follow first. )

1: Strip down your ZMR, check if the Flight Controller fits the holes. *If not, you will have to drill 3, 3mm holes to make it fit ( I had to used a big hammer drill but did the job ). MAKE SURE YOU CHECK WHERE YOU ARE PUTTING IT! DO NOT DRILL THE TRACE LINES.
2: Turn over the PDB and solder on the supplied LEDs. You get 3 white and 1 red. You’ll have to check which is which. + to +, – to -.

3: Solder on your + and – leads to the pads at the end, front or back. ( back is with DTI on ) for your battery with connector on. Test the board works by plugging in your battery. The LEDs will light up.

4: Attach the Flight Control Board.

Now time to prepare the ESC’s.

5: Make a note of which motors go where (I numbered mine and drew a picture so I know the correct way).
Your ESCS should have 5 wires coming off 1 end, 1 red +, 1 black -, and a 3 strip. ( Signal, red + and brown/black – ) You only need the main + and – along with the signal wire (usually yellow/white). So pull the signal wire from the strip and snip the other 2 down. Do this for all 4.

6: Line up your frame arms with your ESC and motors on in the correct order. ( Remember the FC should have an arrow on it pointing to the front ) Attach the arms to the PDB and snip down the ESC wires to length and solder them to the correct points. Red to +, Black to -, signal wire to the O. Repeat for the other 3.

7: This is the main part and fiddly bit! Connecting them all up to the FC! As you can see on your PDB, there are 6 holes next to your FC area. 1 +, 1 -, and 4 o’s. Those 4 o’s are for the signal wires. ( They go in this order, Negative, Positive, ESC 4,3,2,1. So, left to right if you have the holes near you. )

8: Strip down your spare servos ( The black connectors ) And put 3 of the signal wires you snipped off into it. ( They should still have the pins on them. ) Now, with another servo, make 1 with Black -, Red + and Signal o.

9: The FC I used was a MultiWii 2.5. So, my connections were not near the soldering points. So, check the length of wire you need and snip down.

10: You need to solder the new servos you’ve made to the soldering points. The first one, with Red +, Black -, signal o, goes into Red +, Black – and 1 ( The last hole ). Then the ESC Servo 4,3,2 goes into the next 3 holes.

11: Once they are soldered, you need to connect to the FC.  You need the Red +, Black -, signal o, servo on ESC 1, then the next servo only needs to connect to the signal pins on the FC.

12: If you have a FPV camera, now you can solder it to the  pads. ( But remember to always have your ariel attached or it’ll fry. ( Or something )

13: Connect up your TX and battery, test all motors are working and spinning the right way. If all is well, assemble your quad back together!

If your motors are spinning incorrectly,  then swap pins over on the FC till it’s right.

If you’re ESCs are not calibrated at this point, you need to disconnect all servos from your RX and connect your main servo from your FC ( The Red, black and signal ) into the channel for your throttle. (It was channel 3 for me ) and proceed with your calibration, to calibrate the rest, just swap the signal wires over from the 3 signal servo into the main servo (I numbered them all with a little bit of sticky label).


If you use the Diatone PDB as I think it’s intended, i.e. on the bottom below the ZMR bottom plate then you wouldn’t be drilling anything anyway, or do it your way but use a modern flight controller.

4 thoughts on “Drone kit – ZMR250 PDBs”

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