Re: Tell me your favorite uBitx mods
As far as alignment is concerned, if the new board has holes over the locations of the Pots on the uBitX board then that at least can be done without service cables or board removal.
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On Jan 1, 2018, at 6:56 PM, Jerry Gaffke via Groups.Io < jgaffke@...> wrote:
This new board will hide all the parts on the uBitx, servicing will require a cable set to split the boards.
Might be better to flip over the uBitx.
Alternately, mount the new board under the uBitx with any surface mount components facing down.
?
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I like to take a bit mapped image of something and paste it into my drawing program. ?Then I use it as a guide to drawing the object. ?Now I have a vector image of it which can be scaled up indefinitely.
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i draw them in inkscape. they are simple symbols to make. if you use the same thickness of lines eveeywhere, then they look consistent.the other thing to do is to scrap them off arrl handbook'a pdfs.
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Re: Tell me your favorite uBitx mods
At first I had some erratic keying. The contacts of my vibroplex paddle
had to be cleaned as the contacts were
showing a few 100 ohms and this was freaking out the Raduino. The keying
is done by the resistance across the
input.
I agree with erratic tuning. Sudden jumps is annoying and is waiting to
be tackled at my bench.
Raj
At 02-01-2018, you wrote:
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3 Days getting familiar with
the MicroBITX...
CW Keying as is - isn't really usable.?? Critical on the fix it
list.
It misses the first dit or even dah and the faster you send with the
paddle, and the longer you send the worse it gets.
10 WPM is barely usable with errors and 25 to 30 WPM (typical CW speeds)
it is completely unusable.
Whether this is RF riding on the paddle inputs or code changes necessary
I don't think has been resolved.? ?
A little more time with these to sort this out - time will tell if
anything external needs to be dealt with.
Erratic Tuning - Erratic Operator?
Tuning seems a bit erratic and I don't know if a better operator or a
better quality encoder would help.?? LOL
It can start stepping at 200 to 400 KHz to MHz when moving across an
Amateur Band at what seems like steady tuning speed?
This really shows up when moving from CW portion to Phone portion of the
band (e.g. 7.025 to 7.280).
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i draw them in inkscape. they are simple symbols to make. if you use the same thickness of lines eveeywhere, then they look consistent. the other thing to do is to scrap them off arrl handbook'a pdfs. - f
On 2 Jan 2018 2:04 am, "Jeffrey Peters" < dek9jp@...> wrote: Hello Ray,
Great question. I just googled symbols for each morse code key, headphone, and microphone. The Google images webpages had lots of symbols for each.? Now, to see if there is a better place to find them. HNY, Jeff K9JP
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Re: Tell me your favorite uBitx mods
3 Days getting familiar with the MicroBITX...
CW Keying as is - isn't really usable.? Critical on the fix it list. It misses the first dit or even dah and the faster you send with the paddle, and the longer you send the worse it gets.
10 WPM is barely usable with errors and 25 to 30 WPM (typical CW speeds) it is completely unusable.
Whether this is RF riding on the paddle inputs or code changes necessary I don't think has been resolved.?? A little more time with these to sort this out - time will tell if anything external needs to be dealt with.
Narrow 500/600 Hz CW Filter?- The bands are crowed here... May really only be a PCB layout change for a later rev? with optional component loading??? I think important. I'm guessing 50% QRP's are CW Ops.
SSB Modulation -?I no longer think a Mic pre-amp is needed except for typical HF Electret Mics like ICOM etc. have much lower output, but they easily drive KX2's & KX3's. The supplied Mic drives the stage with LOUD voice and my SmartPhone/Tablet?PC headset drives almost identically (except the headset has an exceptional noise cancelling aviation Electret Mic) Maybe just adjust the Audio Stage Gain with a Set and Forget Pot on PCB - This I can try while monitoring for distortion. Power however is --- 80M is 15W CW, 12W PEP, 40M is 3W PEP unless yelling into the Mic so look then below...
Output Power vs Frequency - I see now the main issue is rapid fall off of output power w/freq.
Power drops from 80M 15W to 40M 7.5W to 20M 3W and so on down to 0.4W on 10M (all CW) Filter shapes look good with flat output across the bands! Maybe a shift to Mitsubishi RD16HHF-1 MOSFET is worth a try. Need to check proper BIAS for idle current on the Mitsu parts and watch on the Spectrum Analyzer while tweaking.?? I wonder if Ashhar Farhan has tried these?? They are everywhere from $5 each here in the US to US $0.85 (China) in lots of 10.
Erratic Tuning - Erratic Operator? Tuning seems a bit erratic and I don't know if a better operator or a better quality encoder would help.? LOL It can start stepping at 200 to 400 KHz to MHz when moving across an Amateur Band at what seems like steady tuning speed? This really shows up when moving from CW portion to Phone portion of the band (e.g. 7.025 to 7.280).
Overall a stunningly well done Kit.? - Thanks to the whole team! I'm really impressed that the only assembly issue was the Wire-Up schematic with Yellow and Orange leads reversed to the Volume control.? Please correct and post the correct wiring diagram.? - Pictures of course tell the truth (if you look.) . RTFM LOL
The radio came up the first time playing well and all alignment was spot on.? I only adjusted the BFO - 11.996.5 seems about the best listening, but I haven't looked where that is on the skirt yet? (20dB down) vs TX Audio. Initially I was suspecting that might account for the weak PEP figures on SSB vs CW before I saw the rapid drop in power vs Freq..?
Happy New Year everyone.??
Those waiting, you're going to have fun with your new radio when it arrives.
Dave WI6R
On Mon, Jan 1, 2018 at 1:27 PM, Diver Martin <diver.martin@...> wrote: Not sure how I could do CW filter mods without significant mods.? What I'd like for most of the mods is one-wire in, one wire out.? Narrower CW filtering can be achieved by changing the cap values on the Bitx, so that's not one I'd probably aim for. When you say clean keying for CW, I assume it's clicky, and has sharp edges?? Could be doable with a keyshaper on the output of the CW Tone.? I'll consider it. QSK:? Pretty significant modification, one I'm not going to attempt with this pass I think. Digital mode audio/PTT:? PTT in the works, digital mode would just require isolated transformers, no? AGC: In the works :) SWR Gauge:? In the works :) ATU:? In the works :) CAT Control:? In the works :)
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Does it receive ?
Shake all trifilar toroids and any shorts may show up.
Check all the yellow toroids for bad solder.. check continuity with multimeter in beep mode..
Raj
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At 02-01-2018, you wrote: Finally got around to putting my ubitx into a box, and I'm having trouble getting measurable output. I followed the bias tuneup procedure but when I got to the part where you HAAALLLLOWW into the mic and watch for deflection on the ammeter, I got none. I also didn't see any movement on the power meter/swr/dummy load. So I hooked up a cw key and confirmed: no measurable output when keyed down.
Where ought I to start troubleshooting?
Thanks much and 73
Joe KD9JLV
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Re: Variable power control
Take a look at this,?
I am trying to figure out a way to use this inline with the PA power supply to be able to control the output power from software. Just brainstorming, but if you had a spare pwm pin and buffered its output with some capacitors into a transistor controlling the power rail, it might be doable. But I am really new to all this and am just looking at projects to try when my kit comes in.
Someone feel free to poke a hole in this and save me from wasting an afternoon if this isn't on the right track for a software controlled solution...
--
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N5WLF, Greggory (or my nickname, Ghericoan)
General Class, Digital Radio Hobbyist
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Re: Tell me your favorite uBitx mods
The only things requiring a cable/wire are the AGC mods.? All the rest interface with the existing headers and would just plug in.? Noted though... could make it a cable that's easy to remove.
On Mon, Jan 1, 2018 at 6:56 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote: This new board will hide all the parts on the uBitx, servicing will require a cable set to split the boards.
Might be better to flip over the uBitx.
Alternately, mount the new board under the uBitx with any surface mount components facing down.
?
-- Martin Held - AE7EU
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If there aren't any questions, then what is there to learn?
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Re: Tell me your favorite uBitx mods
This new board will hide all the parts on the uBitx, servicing will require a cable set to split the boards.
Might be better to flip over the uBitx.
Alternately, mount the new board under the uBitx with any surface mount components facing down.
?
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This has been very useful to me so I'll share it in case it is useful to others.
I have written an Arduino sketch that provides a simple command-line console (serial) to control most features of an Si5351/A.? This provides a very generic tool that can be used during the early phases of home-brew rig development when you just want to get the RF/IF chain up and running in a minimal way without fooling around with displays, encoders, Arduino coding, etc.? Just load up this sketch, connect the I2C pins to the Si5351/A, open he Serial Monitor (or other terminal program) and you're ready to start tuning.
There are some handy features that make it easy to deal with superhet math and filter pass-band tweaking. The details are here:?.
I'm doing a scratch-build of the BITX-40 with some modifications so I've been using this sketch a lot.? For my BITX I use CLK0 for the VFO, CLK2 for the BFO, and CLK1 as an RF signal injector/tester.? Here is a video of the receive side up and running:?
Happy New Year and 73s,
Bruce KC1FSZ?
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Happy 2018 for everyone in everywhere.
Here something I am doing before to test the board for a 'modular rig"
This is the Qrp PA (100 x 33 mm)from the Bitx40v3 schematic with small change in the toroid winding.
I used a IRFZ44 and the Qso with Cuba from Cape Coral, FL is excellent in the morning around 9:30am (EST)
I made a Qso last Sunday, Dec 31st and today.
I am very happy with AllPcb, they charge $5.000(plus$0.45 Pay Pal fee) for 10 board with free delivery to USA for free, fast and inexpensive for test.
I have found JLCpcb with $2.00 for the same area with DHL free delivery, I will coment here after I use it.
Tomorrow I will to get the other board with the exciter (100 x 100 mm) to use with this PA, all inside a DVD recycled metal box enclosure.
You can find more inf here in my FB wall
https://www.facebook.com/groups/QrpCuba
or email to wj6c
Have a good night
Qrv's
73's Jc
?
?
?
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Re: #ubitx Power output on 40 / 80 m with high current levels
#ubitx
Layout is important, as John has said.? I'd suggest a very short source lead soldered directly to the ground plane,
keep the drain lead well separated from the other two (Allison suggests clipping the drain lead off and soldering to the tab),
and try adding a 10 ohm resistor in series with the gate.
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On Mon, Jan 1, 2018 at 05:26 pm, John Backo wrote:
So it is likely that you are seeing VHF oscillation drawing the extra current.
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Re: #ubitx Re: Ubitx only on preorder now
#ubitx
Correct, a custom clearance fee but there should not be any taxes.
On Mon, Jan 1, 2018 at 8:56 PM, Michael Babineau <mbabineau.ve3wmb@...> wrote: DHL will charge a customs clearance fee and ?HST will be applied to the value of the goods on top of that.?
For the BITX40 the extra charges were around $Can 30, so it will be more for the uBITX.
Michael VE3WMB?
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Re: #ubitx Re: Ubitx only on preorder now
#ubitx
DHL will charge a customs clearance fee and ?HST will be applied to the value of the goods on top of that.?
For the BITX40 the extra charges were around $Can 30, so it will be more for the uBITX.
Michael VE3WMB?
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Re: Tell me your favorite uBitx mods
So, this is roughly what I'm thinking for the layout thus far.? Here's what you're seeing thus far:? uBitx is underneath the PCB on .5" standoffs (Supplied with the uBitx kit).? The uBitx itself is 1/4" away from the bottom** of the case.? PCB mounts on top.? Upper left:? Power input, 2x (one for 8V+, other for 12V or PA power, default is to just use the 8V+ line, a relay can change the PA power).? ?Going counter-clockwise, 5V regulator (I'm going to move that to the lower side of the PCB and use the .1" header from the raduino instead, so that +5V doesn't cross under the RF path), BNC RF output, DSP audio output, Teensy 3.2 control module (Due to higher power MCU w/ dsp capability), Key jack, PTT jack.? There's plenty of room for an AGC mod, the raduino header, and the audio connector.? Right side, the vendor I use for PCB's has options of 15cm x 20cm, so I made use of the extra space on the right to create a 'front panel' pcb.? So Mic and headphones on the front (blue comment layer circles show where the audio jacks would pop out), and one would break off the additional PCB that contains a variable pot for audio gain, encoder (reused from uBitx kit), some pushbuttons (for whatever function you want), and then the HD44780 display shipped with the raduino.? Two headers so that it can be mounted upside down or however you wish.?
**(or top of case) I did this because some people might want the display on the right side of the unit, others on the left, and this can be easily achieved by simply flipping the entire thing upside down in the enclosure.? I'm not sure if the HD44780 can be flipped upside down (I can't see why not), but just in case, footprints are free, would be up to the user to decide where it gets soldered in.? There's a 595 shift register for the display as well.? One thing not shown yet are the connections for right angle .1" headers that would connect the front panel to the main board, easy enough to add later, just haven't done it yet.??
Going back along the top, SWR Bridge components, and the lions share of space for the tuner, and a cutout notch for the uBitx heatsinks.
As you can see, plenty of room on the system for mods.? Just... harder to get front panel space :)
So, full list of features: AGC(Pending design, feedback is good! - include S-meter) Tuner Fast MCU w/ USB back panel access [cat control] Dual power supplies for TX pwr DSP audio output Keying interface Pushbuttons for the front panel SWR Bridge Linear control (Pending, Just a cheap reed relay hooked up to the PTT line basically)
I haven't even thought too much about how much it'd cost to make,? Probably a significant amount :)? I'm putting single-unit costs in my components in the schematic, so that I can take a guess at just the raw BoM cost eventually, but all in due time.
On Mon, Jan 1, 2018 at 5:03 PM, Diver Martin <diver.martin@...> wrote: So looking at the schematic, it's basically an IF amp (MC1350P, which is obsolete/harder to get, though I have gotten them from Jameco before) with a dual gate mosfet as the attenuation stage.? The rest is just a separate amplifier (Q504-509) and a detector diode (D502) feeding that gate.
What I would ultimately want to do I think is provide one input, and one out on the add-on PCB that I'm doing, and maybe cut at Q30 on the uBitx to get the RF input.? To do the mod, one would cut the trace as indicated, and then solder in some 30ga wire that goes up to the motherboard, which provides the modification.? I'm thinking Q30 is probably the best place to put the AGC, as after the 12Mhz narrow filter, there is no other amplifier, so I'm kinda limited to the 12kHz bandwidth filter to do the AGC I think.
-- Martin Held - AE7EU
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If there aren't any questions, then what is there to learn?
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Re: #ubitx Power output on 40 / 80 m with high current levels
#ubitx
Alex:
What you are doing is all the right things to find the right combination
to drive the IRF510's. Get a hold of and really read the original article by WA2EBY
for all the things he discovered along the way. The primary thing is taking care of heat.
You seem to have accomplished that. The second is coming up with the proper layout to eliminate
the propensity of the finals to oscillate -- that is probably what you are experiencing.
"I'm working on my uBitx which is completely homybuilt, so not the currently sold PCB version. By building it from scratch you encounter a lot of interesting things and learn a lot about it. Receiving of the rig is very good now but I am struggling with the TX. When aligned for output power of 8 watts, using a sine wave generator and full modulation level, the rig draws about 3,5 amps of current on 40M. At 80M, power output increases to about 12 watts, but current jumps up to around 4 amps. Sometimes my IRF's get killed at that level. There's now way so far I've got it set to say 8 watts with less than 2 amps of current. Things I've done so far are:"
Are you sure you are using SSB? And the amplifier class is really AB? Remember, SSB output is Pk-Pk, while AM is "100% modulation". I would be interested in
seeing if there is any carrier output. This sudden current jump is suspicious of extra oscillation.
"Play around with the HF power gain pot RV1 in combination with more audio drive level"
Don't go above 3v or so on the IRF gate. Maybe even 2.5v. These are very touchy devices and hit a full on current condition with no warning...as you have
already found out.
"Play around with the IRF's bias adjustment. Setting it too high will give a current thermal runaway and a fried IRF within a second. Careful with that...
Output toroids of the IRF balance, changed the windings bifilair, trifilair en more in both directions, so in fact play around with the output impedance with the IRF's see. The trifilair original option seems to be the best bet, but with these high current values. Toroid is a 37-10 with 7 windings trifilair.
Changed the emitter resistances on the 2N2219 to decrease the input power."
IRF MOSFETS are notorious for being extremely variable. You are right that a different batch will give entirely different results. The use of #10 material for the toroid is very good, but I would increase the size to at least a T50, and probably would go to a T68 or even a T100 for high power levels. It doesn't take much to saturate a T37, and then the transformer is an entirely different one. Also, it might be prudent to look for a different form factor for the output transformer, one with a bit more shielding than a toroid. I know, they have a good
reputation, but they are not perfect in a strong RF field.
"I've measured the LPF and it has a cutoff at 7300 KHz so that should be fine.Testing done at 12volts, when at 13,8 volts, the output power and IRF amp values increase dramatically (got over 16 watts of RF) but this often kills one of the IRF's. No way I would keep the IRF's alive on 24 volts.
I don't have the LPF's for the higher bands in place yet, but it seems that at 20m and higher the overall gain of the TX chain decreases. When measured WITHOUT LPF (yes on dummy load, for sure) output power decreases to less than a single watt... This could also be an effect of the bidirectional part of the TX chain where the gain decreases with higher frequencies. For now I'm concentrating on the difference between the behaviour at 40 and 80 meters."
It's unlikely that the bidirectional amps have much to do with radiated power...provided the throughput is adequate. In the case of the BITX, that is roughly 10 dB.
Know also that the IRF510 is not a very good device above 40m. Yes, they can be made to work well, but it takes a good impedance match and heat control to
do so. They also work better at 24v than at 12v. So it is likely that you are seeing VHF oscillation drawing the extra current. That will SEEM like the output to the
antenna is better, but it really is not. Offhand, I would say that you have a layout problem and are using a little too small toroids to handle the load. You might consider
divorcing the final amplifier from the rest of the rig, and working out the rest. Farhan designed the uBITX for a wide range, but rather low power output -- certainly less
than the IRF510 is capable of handling. Any experimental work is good, but it is really in a different league here. I like what you are doing...it is pushing the design into new territory.
john
AD5YE
"Could it be I am just using a wrong brand of IRF's? I have a load coming in from a second supplier to check.
Any other ideas? I have got rechargeable batteries built into my rig and they would last much longer if I could keep the total peak current below 2 amps.
Oh by the way, I've got a very large cooling heat sink and never got it really hot, just 'warm'
Lovely experimental rig!
73, Alex
PA1FOX"
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Re: #ubitx IRF510 concerns, different modes
#ubitx
General rule of thumb is no more than 25 to 30% of the total output of the rig. He always control the output by the audio level in and if you can monitor it back off until the alc Barely indicates.... Otherwise you will become one of those annoying broad splatter stations
On 1 Jan 2018 6:18 pm, "Ghericoan" < boakawizkid@...> wrote: I have yet to get my ubitx yet, as I am on the preorder list. But I was wondering if there is a way to back the power output down to five watts to save the heat stress on the IRF510s. I am looking to do digital modes like PSK31, WSPR, and possibly playing around with SSTV.
Just concerned on how to go about assembly once the unit is here because I want it to be solid for digital modes. I have already ordered spare MOSFETs, but would rather not get into the habit of replacing them.
--
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N5WLF, Greggory (or my nickname, Ghericoan)
General Class, Digital Radio Hobbyist
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Re: #ubitx IRF510 concerns, different modes
#ubitx
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On 1 Jan 2018 6:18 pm, "Ghericoan" < boakawizkid@...> wrote: I have yet to get my ubitx yet, as I am on the preorder list. But I was wondering if there is a way to back the power output down to five watts to save the heat stress on the IRF510s. I am looking to do digital modes like PSK31, WSPR, and possibly playing around with SSTV.
Just concerned on how to go about assembly once the unit is here because I want it to be solid for digital modes. I have already ordered spare MOSFETs, but would rather not get into the habit of replacing them.
--
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N5WLF, Greggory (or my nickname, Ghericoan)
General Class, Digital Radio Hobbyist
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Re: Tell me your favorite uBitx mods
So looking at the schematic, it's basically an IF amp (MC1350P, which is obsolete/harder to get, though I have gotten them from Jameco before) with a dual gate mosfet as the attenuation stage.? The rest is just a separate amplifier (Q504-509) and a detector diode (D502) feeding that gate.
What I would ultimately want to do I think is provide one input, and one out on the add-on PCB that I'm doing, and maybe cut at Q30 on the uBitx to get the RF input.? To do the mod, one would cut the trace as indicated, and then solder in some 30ga wire that goes up to the motherboard, which provides the modification.? I'm thinking Q30 is probably the best place to put the AGC, as after the 12Mhz narrow filter, there is no other amplifier, so I'm kinda limited to the 12kHz bandwidth filter to do the AGC I think.
On Mon, Jan 1, 2018 at 2:29 AM, Dave Bottom <ars.kd6az@...> wrote: Martin,
The Heathkit SB-104/A/HW-104 has an uderly simple AGC system that works so well it was easily the easiest rig to just sit and read the mail.? Round tables with so many different strength signals and it was so pleasant to listen to.? Just a dual insulated gate FET ahead of the IF Gain and there are 8 transistors in the AGC Amplifier, Fast/Slow AGC and S-Meter output.
Schematic attached of SB-104A.
Dave
I actually had a couple of pre-amps for a hi fi project, but used for this Kit 98, works, but there are simpler circuits.
Dave WI6R
-- Martin Held - AE7EU
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If there aren't any questions, then what is there to learn?
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Re: Tell me your favorite uBitx mods
You save on package count with the TPIC6B595.
It¡¯s basically an HC595 with 150 mA sink drivers.
<>
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Figured out what my plan was on that front.? I want to re-use as much of the raduino as possible, so one thing I did to make my life easier was to use a 74HC595 shift register, frees up IO's, and uses ones I've already got to level shift up to 5V for the IO expanders (the relays are all 5V that I'm using / have already designed in).? This way, the stock display module that comes with the raduino can be used.
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Raj vu2zap
Ghericoan
JuanCarlos Berberena Gonzalez
Art Howard
