ce v1.2 on a ubitx v5

Nick Tile

I've been trying to get Ian's firmware running on a uBitx V5 by loading it to a new Nano to replace the one supplied in the raduino - the firmware loads ok, but when I swap the Nano, its dragging the supply to the display down as though there's a short (the regulator on the raduino gets very hot very quickly). 

I've tried loading various versions of the firmware in case I have a different display - I don't think I have, its a standard 1602 16 x 2 but to no avail so I wondered if there's something really obvious that I'm missing.The "new" nano loads ok so I thinks its alright and the radio is fine with the standard supplied nano.

Bit puzzled ...

Nick Tile

belay my last - I spotted my idiot mistake - sorted !!


If you are using a Nextion display, remember that depending on the size, those draw more current, so it is recommended an additional regulator on the case.

On Wed, Jul 10, 2019 at 11:32 AM Nick Tile <juggie@...> wrote:
belay my last - I spotted my idiot mistake - sorted !!

Bill Lamm

Do share for the next guy with same problem :-)

Ian Reeve

In my ubitx I have a 3.5" Nextion display and find the onboard 5v regulator with a finned Heatsink manages OK.Gets warm but not too hot to touch,a external chassis mounted 5v regulator would be a better option,just remember to fit filter ceramic caps on input and output. 

From: <> on behalf of Bill Lamm <kd9mdl@...>
Sent: Thursday, July 11, 2019 3:15:08 PM
Subject: Re: [BITX20] ce v1.2 on a ubitx v5
Do share for the next guy with same problem :-)

Evan Hand

The other option is to install a voltage dropping resistor in series with the input to the 5 vdc 7805 regulator as well as adding the heat sink (with thermal compound).  I added 2 - 2 ohm 2 watt resistors in series (4 ohms 4 watts total).  That dropped the heat of the regulator significantly.  I then tested a 5 ohm 10 watt resistor on the 5vdc output side while running the rig.  There was a slight drop in voltage, less than .2 volts, and no impact to the the rig performance.  The regulator will get very hot with 1+ amp, though not into thermal overload. My estimated total current draw was 1.15 amps for this test.

Still, the best solution is to run separate regulators, as that way you have less dependency on input voltage.  With the voltage dropping resistor, under heavy load, the input voltage needs to be above 11 volts into the rig.  This drops as the 5 volt current drops.  The regulator needs at least 7 volts in to perform correctly,  All this is in the 7805 data sheet.

Above is my experience.  YMMV

Nick Tile

For the benefit of Bill Lamm, I did say that it was an idiot mistake, and it was. The Nano is inverted in the socket compared to the way that they're usually connected so if you solder up a fresh Nano to use, you need to get it the right way up in respect of the pins ... doh !! I had had a very long day and was half asleep ...