A replacement for the DM More Pro Mini Strong

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Mike_K
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Joined: 16 Feb 2018, 06:35
Location: Hertfordshire

A replacement for the DM More Pro Mini Strong

Post by Mike_K »

Pro Mini Encoders with a Pro Mini Strong for Comparison
Pro Mini Encoders with a Pro Mini Strong for Comparison
Headers and 0.1" jumpers can be used in the place of a DIP switch
Headers and 0.1" jumpers can be used in the place of a DIP switch

As I become more familiar with KiCAD, I wondered what else I could draw up. This coincided with Stuart Mackay having some problems with a bad batch of DM More Pro Mini and I wondered if I could do a DM More copy, but more customised to our use. After discussing with Stuart his wish list, we came up with the following:
  • Same 40mmx40mm dimensions of a Pro Mini Strong
  • Pin compatible with the Pro Mini Strong, so it would run Phil's 7 channel encoder or my modified "F3A" version of his encoder without program change
  • The battery in and encoder power out connectors in similar positions to existing, with no "links" needed
  • Reverse polarity protection (we remove the DM More Pro Mini Strong reverse polarity protection Schottky diode, to fit the link to get the battery voltage to the 3-pin ppm/power for the 2.4GHz module)
  • The sounder to be on-board and to be powered directly off the battery voltage, so it doesn't put an additional load on the voltage regulator. Still use an emitter-follower so it stays as a 5V sounder
  • A zener diode and pot' to drive the existing meter on most transmitters - the pot to adjust full-scale deflection
  • The DIP switch pads the correct distance apart (0.3"), so the legs don't need bending/forming to fit
  • Fit another row of pads 0.1" apart, so two rows of headers could be fitted for use with standard "jumpers", as an alternative to the DIP switch
  • Split the analogue inputs into two banks of four with a small gap between them, as it's difficult to fit 8 plugs into the existing header - most servo plugs are fractionally wider than 0.1", so the last plug to be connected are always displaced sideways and difficult to connect
  • Omit the reset switch and the D13 header, as the sounder is onboard and connected via a transistor to D13
  • A red smd LED for power and a green smd LED on D13 to indicate the sounder
  • DIP switch Sw2 not connected to D0, so if it is accidentally switched, it won't short the ppm signal to ground (it saves cutting the legs of Sw2
After a bit of shuffling the components around, everything fitted on the board and I think all the design criteria have been met. Obviously, it can't quite compete on price with the mass-produced DM More board, but I think it'll be close enough to tempt some people to consider it.

But before I had even received the boards, I'd already designed a MK2 version with some other idea's. The sounder was very close to the DIP switch and if a different brand of DP switch was used it could foul the sounder. And it seemed a shame to have to solder a through-hole zener diode on-board and not have a surface mount version. I always use a 6.8V zener for the meter and Phil uses a 6.2V zener, hence why I thought you'd fit one to suit. But I realised I could put a 6.8V and a 6.2V smd zener on the board, on different pins of a 3 pin header and the cost would be less than one through-hole version.

I then did an MK3 version to use the ATmega328PB, the follow-on-model to the normal ATmega328P used in Arduino. It has two additional inputs (it changes a 5V and a GND connection for the additional inputs). We could use one to wire up all 8 of the dip switches as there wouldn't be a conflict with the ppm signal on D0. And I've added a low voltage alarm circuit using a zener and transistor. Not everybody thinks that a low voltage alarm is essential, but if it would fit, why not? And the other switch? Well I know some are already using the modified "F3A" version of the encoder, others like Phil, still prefer the original. There's plenty of flash memory to have both programs integrated together and Sw2 Off = original and Sw2 On = F3A.

Virtualisation of the MK3 Pro Mini Encoder - the sounder and pot' are slightly smaller in real life
Virtualisation of the MK3 Pro Mini Encoder - the sounder and pot' are slightly smaller in real life

I've sent out a number of the boards to members on the forum for comment and also ordered some MK2 and MK3 boards, to compare.

Cheers

Mike
Tobe
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Joined: 16 Feb 2018, 06:19
Location: Varberg or Stockholm, Sweden

Re: A replacement for the DM More Pro Mini Strong

Post by Tobe »

I love this evolution! Thank you for sharing it.

If progress continues at this paste soon there might be a shortage of transmitter to convert in decent shape with only Stuart able to find good conversion candidates!
Cheers,

Tobe
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Wayne_H
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Joined: 17 Feb 2018, 05:26
Location: Temora, NSW. Australia
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Re: A replacement for the DM More Pro Mini Strong

Post by Wayne_H »

Well done Mike ;)

I have more projects than I can poke the proverbial stick at :o , but I'm keen to try a couple of boards when they are ready.
Cheers,

Wayne
Once a Retrobate, always a Retrobate............ ;)
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_AL_
Posts: 160
Joined: 17 Feb 2018, 01:09
Location: Sydney Australia

Re: A replacement for the DM More Pro Mini Strong

Post by _AL_ »

Looks good.
I've dropped off 95% of the hobby for a while due to some health issues & 75 hour work weeks but I hope to have some spare time back soon.
I'm interested in a couple of the boards at some point in the future if available.

Al
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tiptipflyer
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Joined: 16 Feb 2018, 22:49
Location: Germany

Re: A replacement for the DM More Pro Mini Strong

Post by tiptipflyer »

Great idea Mike. Well done. It will make things easier.

Frank
Pchristy
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Joined: 16 Feb 2018, 13:57
Location: South Devon, UK

Re: A replacement for the DM More Pro Mini Strong

Post by Pchristy »

Wow, Mike! That is excellent work! I've not currently got any conversions on the go - more Tx's than I know what to do with at the moment! But I'll certainly bear these in mind for my next project - if it ever happens!

Between you, Tobe and Phil, we almost have enough to re-start manufacturing again in the UK!

:D

--
Pete
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stuart mackay
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Re: A replacement for the DM More Pro Mini Strong

Post by stuart mackay »

Super excited as a test example from Mike's first batch arrived today and intend to install this weekend in my Pro-Line with one of the new Lemon RF modules to flight test, hopefully in the Moonglow, once we are allowed!

Thanks Mike, & love the added integration, layout and features/component upgrades that Mike has included on these. The changed pin spacing makes installing eight plugs on the input side much more convenient now!

Looking forward to this great upgrade based on practical feedback. :lol: :lol:

Just to be clear, The issues that Mike referred to that I had been facing with the DIYMore were based on a pulse counter that had a faulty switch which I use during the builds and had been giving false results when testing.... indicating that the boards had failed, :roll: :oops: which yesterday, Mike and I established was not the case, so please dont worry if you are using or want to use a DIYMore board!.
Last edited by stuart mackay on 21 Mar 2021, 06:55, edited 1 time in total.
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stuart mackay
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Re: A replacement for the DM More Pro Mini Strong

Post by stuart mackay »

Tobe wrote: 18 Mar 2021, 20:18 I love this evolution! Thank you for sharing it.

If progress continues at this paste soon there might be a shortage of transmitter to convert in decent shape with only Stuart able to find good conversion candidates!
Nice compliment Tobe, thanks :oops: :shock: but, sadly, I think I might have now "drained my pond dry" of suitable transmitters from my contacts in the hobby :( :(
stormer254
Posts: 91
Joined: 03 Mar 2018, 10:08

Re: A replacement for the DM More Pro Mini Strong

Post by stormer254 »

stuart mackay wrote: 21 Mar 2021, 06:47
Tobe wrote: 18 Mar 2021, 20:18 I love this evolution! Thank you for sharing it.

If progress continues at this paste soon there might be a shortage of transmitter to convert in decent shape with only Stuart able to find good conversion candidates!
Nice compliment Tobe, thanks :oops: :shock: but, sadly, I think I might have now "drained my pond dry" of suitable transmitters from my contacts in the hobby :( :(
Certainly Stuart made a big dent in my loft but I still have quite a few single stick sets and some original single channel sets left!!
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PaulJ
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Joined: 16 Feb 2018, 19:01
Location: Ipswich, UK

Re: A replacement for the DM More Pro Mini Strong

Post by PaulJ »

Stormer, pm sent.......

Paul
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