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Looking for responses and opinions on what people are using for reverse polarity protection on the sBitx?
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-JJ
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Reverse polarity power is definitely an issue for those who might not use connectors that can be only plugged in one way. If the radio would function at full power on slightly less voltage, a full wave bridge rectifier would solve the problem completely.? The drawback to that approach would be extra voltage drop and current consumption. I premake all connectors to match the radio socket, which is a reasonably good choice, in my opinion. Then, being paranoid,? I verify with a multimeter before connecting. For portable, I connect to a large car jump box battery. For home use, I have a connector going to my 12 volt supply.
Accidents happen, voltmeters help minimize their occurrence. Don't get in a hurry.
Scotty WD4PYT
Looking for responses and opinions on what people are using for reverse polarity protection on the sBitx?
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-JJ
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I sell a 20A and a 50A reverse protection kit… ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois ? Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ?
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From: [email protected] <[email protected]> On Behalf Of JJ - W9JES
Sent: Thursday, September 12, 2024 10:52 AM
To: [email protected]
Subject: [BITX20] Reverse polarity protection on the sBitx? #sbitx #sbitx_v3? Looking for responses and opinions on what people are using for reverse polarity protection on the sBitx?
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I removed the tiny diode and installed a 10A10 across the two lugs on the power connector. I run a 10amp fuse and it blows it immediately. I tested the diode before installing one in the radio. I have not tried it with the radio but it should work.?
David
Looking for responses and opinions on what people are using for reverse polarity protection on the sBitx?
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-JJ
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Good job! I noticed the mismarked board when I had to change out the board under warranty. I am glad you mentioned it for those unaware.?
Scotty WD4PYT?
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I soldered in a 30 amp diode as a reverse shunt; 30 amp is what I had laying around.? Note that the markings on the sBitx circuit board where the power comes in are reversed.? That plus sign on the board should be a negative.? I know the solder job looks bad but I did put a lot of heat to it.? I just couldn't get it shiny.? What is good about this diode is it can trip the circuit breaker on my 20 amp Astron before I even turn the sBitx power on.? I still went ahead and added a 10 amp blade fuse to the external power pigtail for extra protection.. ?
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I soldered in a 20 amp diode(20A10) as a reverse shunt; it's what I had laying around.? Note that the markings on the sBitx circuit board where the power comes in are reversed.? That plus sign on the board should be a negative.? I know the solder job looks bad but I did put a lot of heat to it.? I just couldn't get it shiny.? What is good about this diode is it can trip the circuit breaker on my 20 amp Astron before I even turn the sBitx power on.? I still went ahead and added a 10 amp blade fuse to the external power pigtail for extra protection.
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I use Powerpoles for battery and PSU connections.? I also use KC9ON's FET-based devices in place of diodes.? They're good for up to 50 V and 7 A.
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There are also 'ideal diode' boards that are inexpensive.? I've not used them, yet a guy with a Swiss distortion in the signal seems to like them.?
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73, Andy
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I also use the fet method, not as simple as a diode, but voltage drop way lesd
I use Powerpoles for battery and PSU connections.? I also use KC9ON's FET-based devices in place of diodes.? They're good for up to 50 V and 7 A.
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There are also 'ideal diode' boards that are inexpensive.? I've not used them, yet a guy with a Swiss distortion in the signal seems to like them.?
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73, Andy
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Reverse diode and a fuse is all I use on any of my projects. Total cost about $0.50. Voltage drop equal zero.
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Another approach which I have not seen proposed is to
switch the power to the radio with a relay with
contacts of suitable current handling.
The relay coil is fed by a diode so only comes in
when the power is of the correct polarity.
The advantage coming through the relay contacts
is that there is no voltage drop save for the
miniscule resistance of the relay contacts.
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On Sat, Sep 14, 2024 at 09:34 PM, Dean Souleles wrote: Reverse diode and a fuse is all I use on any of my projects. Total cost about
$0.50. Voltage drop equal zero.
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PS another diode the other way round feeding a small buzzer
gives an audible alarm if the power is upside down :-) !!!!!
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On Sun, Sep 15, 2024 at 02:58 PM, Gareth Evans wrote: Another approach which I have not seen proposed is to
switch the power to the radio with a relay with
contacts of suitable current handling.
The relay coil is fed by a diode so only comes in
when the power is of the correct polarity.
The advantage coming through the relay contacts
is that there is no voltage drop save for the
miniscule resistance of the relay contacts.
On Sat, Sep 14, 2024 at 09:34 PM, Dean Souleles wrote:
Reverse diode and a fuse is all I use on any of my projects. Total cost about
$0.50. Voltage drop equal zero.
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I've been playing around with a PCB design that uses a mosfet for reverse polarity protection.? Diodes burn a decent amount of power, this mosfet is significantly less.? It also has over volt protection, and esd/transient protection, and fused.?
I need to stare at the inside of the box to see if there's a way to work it into the box, but I think that's going to be a bit more involved than just making it a dongle/pig tail design.
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PS another diode the other way round feeding a small buzzer
gives an audible alarm if the power is upside down :-) !!!!!
On Sun, Sep 15, 2024 at 02:58 PM, Gareth Evans wrote:
> Another approach which I have not seen proposed is to
> switch the power to the radio with a relay with
> contacts of suitable current handling.
>
> The relay coil is fed by a diode so only comes in
> when the power is of the correct polarity.
>
> The advantage coming through the relay contacts
> is that there is no voltage drop save for the
> miniscule resistance of the relay contacts.
>
>
> On Sat, Sep 14, 2024 at 09:34 PM, Dean Souleles wrote:
> > Reverse diode and a fuse is all I use on any of my projects. Total cost
> about
> > $0.50. Voltage drop equal zero.
> >
>
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Has anybody tried the "ideal diodes" Andreas is describing here: ?
So far I am relying on my Anderson power poles being soldered correctly. :-)
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vy de Hermann AJ4ZS
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Jeff, have you seen Gordon Gibby's notes on a project he did with reverse polarity protection?
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Mike KB2ML
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Thanks Mike, that's very similar to what I've got drawn up.? I have an idea for how to add it to the radio, gimme a bit more time and I'll post on the discord and here to see if anyone is interested.
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Jeff, have you seen Gordon Gibby's notes on a project he did with reverse polarity protection??
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Mike KB2ML
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I wrap the fet around the power plug. I include a led toshow there is power but reversed
On Mon, Sep 16, 2024, 7:30?AM Jeff Duce via <jefe_de_estado= [email protected]> wrote:
Thanks Mike, that's very similar to what I've got drawn up.? I have an idea for how to add it to the radio, gimme a bit more time and I'll post on the discord and here to see if anyone is interested.
Jeff, have you seen Gordon Gibby's notes on a project he did with reverse polarity protection??
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Mike KB2ML
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Hey Jeff,
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I’d be interested and I bet that there would be a lot of other people would be interested.
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Robert, AG6LK?
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Just know that simply using Power Pole connectors is not the answer. They can still be connected with reverse polarity as they do not have keyed connectors that prevent reverse connections. A red connector will mate perfectly with a black connector and all it takes is for someone to become confused in the rush of the moment or perhaps someone introduces a power cord they made with the red and black connectors switched from left to right and then when no one notices this, they plug in and BANG!
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I have a love hate relationship with powerpoles.? I mostly hate them.? They are missing many features that make a good connector, but seem to be heavily used in this hobby because they are cheap and can handle high current.? There's no real keying features
for multipin setups, the contact retention method is weak, there's no connector retention method, there's no strain relief for the wire in the crimp, no strain relief for wire going out of the housing... But I do use them just like everyone else, ha! (For
the same reasons, cheap and high current capability).? I haven't seen any other low cost connectors that has all those features, so we're stuck with either XT65s or powerpoles. At least XT65s are keyed. Okay, done with rant.??
What I was drawing up wouldn't rely on the connectors for reverse polarity protection.? It uses a p-type mosfet with a zener diode.? On reverse polarity, Vgs is high, shutting the mosfet which means no current flow through the mosfet.? There is also an overvolt
protection circuit, and an esd protection diode.? Overvolt protection requires a fuse to prevent damage to the power supply, but it does mean that if you accidentally plug in your radio to a 24v source, you're going to pop the fuse.? I want to go over my design
a couple more times and I'll probably post it on the discord for community review.? It will take some time to get boards made and tested, maybe 1 month or more.
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Just know that simply using Power Pole connectors is not the answer. They can still be connected with reverse polarity as they do not have keyed connectors that prevent reverse connections. A red connector will mate perfectly with a black connector and
all it takes is for someone to become confused in the rush of the moment or perhaps someone introduces a power cord they made with the red and black connectors switched from left to right and then when no one notices this, they plug in and BANG!
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"Jeff Duce" <jefe_de_estado@...> writes: It uses a p-type mosfet with a zener diode. I haven't bothered putting polarity protection on my sbitx yet, but my TeleLaunch rocket launch control system products that run on a nominal-12V SLA battery use the Infineon IPD068P03L3G which is a p-channel FET in an TO252 SMT package for reverse polarity protection. Nearly no drop when things are hooked up correctly since the channel on resistance is only 7 milliOhms typical. The parts are spec'ed for up to 70A at 30V, but we have a self-resetting 30A circuit breaker upstream of them. Works great. 73 - Bdale, KB0G
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Scotty R
K9HZ
WK4DS
AE9J
Tominaz
Gary Eldridge - KC8UD
Bdale Garbee