They are tricky little critters! I had to put two in series for exactly that reason in a uninterruptible power supply/charger system that I designed.?
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On Sep 6, 2022, at 15:25, Max via groups.io <kg4pid@...> wrote:
?
Thanks Jerry, since I know nothing about these devices I had to ask.
Max
On Tuesday, September 6, 2022, 12:05:13 PM CDT, Jerry Gaffke via groups.io <jgaffke@...> wrote:
You can't fully turn off the PFET in this application since the intrinsic body diode allows current to flow from the battery to the rig.? You could add a second PFET in series with this one? but this time have the source pin facing the battery, yank the gate down toward ground to turn it on but be careful to avoid exceeding the Vgs spec.. On Tue, Sep 6, 2022 at 06:58 AM, Max wrote:
I'm curious if a switch could be added to this circuit to turn it on and off? Or better still, could it be controlled via 3.3v or 5v logic with a few extra parts?
?
I need an electronic switch and the added protection sure would be nice. Add in a 1.5KE15A 15-volt transient suppressor diode and a fuse and you have over voltage protection as well.?
?
Max KG4PID
|
Thanks Jerry, since I know nothing about these devices I had to ask.
Max
On Tuesday, September 6, 2022, 12:05:13 PM CDT, Jerry Gaffke via groups.io <jgaffke@...> wrote:
You can't fully turn off the PFET in this application since the intrinsic body diode allows current to flow
from the battery to the rig.? You could add a second PFET in series with this one?
but this time have the source pin facing the battery, yank the gate down toward ground to turn it on
but be careful to avoid exceeding the Vgs spec..
On Tue, Sep 6, 2022 at 06:58 AM, Max wrote:
I'm curious if a switch could be added to this circuit to turn it on and off? Or better still, could it be controlled via 3.3v or 5v logic with a few extra parts?
?
I need an electronic switch and the added protection sure would be nice. Add in a 1.5KE15A 15-volt transient suppressor diode and a fuse and you have over voltage protection as well.?
?
Max KG4PID
|
You can't fully turn off the PFET in this application since the intrinsic body diode allows current to flow
from the battery to the rig.? You could add a second PFET in series with this one?
but this time have the source pin facing the battery, yank the gate down toward ground to turn it on
but be careful to avoid exceeding the Vgs spec..
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Show quoted text
On Tue, Sep 6, 2022 at 06:58 AM, Max wrote:
I'm curious if a switch could be added to this circuit to turn it on and off? Or better still, could it be controlled via 3.3v or 5v logic with a few extra parts?
?
I need an electronic switch and the added protection sure would be nice. Add in a 1.5KE15A 15-volt transient suppressor diode and a fuse and you have over voltage protection as well.?
?
Max KG4PID
|
The trick to searching on Mouser is to select large fields of values for the various parameters.
For example, I selected all values of Rds that were 5 mOhms or less by holding the Control key down
while dragging the mouse across the desired values.
Here's the same search, but I have removed the requirement that the drain current be at least 50 Amps continuous:
https://www.mouser.com/c/semiconductors/discrete-semiconductors/transistors/mosfet/?channel%20mode=Enhancement&rds%20on%20-%20drain-source%20resistance=1.25%20mOhms~~5%20mOhms&transistor%20polarity=P-Channel&instock=y&sort=rds%20on%20-%20drain-source%20resistance&rp=semiconductors%2Fdiscrete-semiconductors%2Ftransistors%2Fmosfet%7C~Rds%20On%20-%20Drain-Source%20Resistance
We now see several PFET's in an old style SOIC8 package with no heat tab,
easy to work with but they can't dissipate quite so much heat.
The most interesting of these is Mouser?512-FDS6681Z, which has an Rds of 3.8 mOhms and a Vds of 30v,?
they have 67000 in stock and another 123000 coming later this month.
I'd tend to skip over the 20v Vds parts if it might be getting used around significant voltage transients,
such as in an automobile.?
Page 4 of the datasheet suggests a temperature rise of somewhere between 50 and 125 degrees C per Watt dissipated,
depending on how big the copper land areas are near the part in the PC board design.
A reasonable figure might be 10 Amps per part if you just solder it to a board, 20 Amps if you have a good strategy to get heat away from it.
For more than 20 Amps, you need more than one part.
At 10 Amps, that would be 10*10*0.0038 = 0.38 Watts of power dissipation, and a temperature rise of 125*0.38 = 47.5 degrees C
assuming not much attention is given to heat dissipation in the PC board design.
This being a simple PFET, the junction temperature is rated for a max of 150 C before it fails (though odds of failure
are rather high if kept anywhere near 150 C for very long).? So ambient temperature (the temperature of the PC board near the part)
should be kept to under 150C - 47.5C = 102.5 C.? So long as the part doesn't get so hot that it sizzles spit, we should be fine.
These PFET's only protect against connecting a battery or power supply with reverse polarity.
For protecting all but the high power parts of the circuitry against too high of a voltage,
I like using a low dropout linear regulator such as the LM2940CT-12, good for up to 1 Amp.
That particular part also protects against reverse polarity, the older LM7812 parts do not.
Jerry, KE7ER
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On Tue, Sep 6, 2022 at 01:37 AM, Gordon Gibby wrote:
That's FANTASTIC of you, Jerry.? ?Much slicker with the online stores than I had been.? ?
I ordered 8 of the IPP80 version just to have a few more around the house since there are hundreds of them -- BUT THEY WONT LAST LONG FOLKS!!
I also updated the Construction Manual with the availability information, giving the link to the available part.??
See:??? ?(now updated with a through-hole? part from your list)?
?
Using the lowest possible Rds-on just makes this so so much easier on the builder.? ?The losses in our existing units through the MOSFETS are actually lower than through the crimped connectors etc in our powerpath.? ?I actually measured losses in fuses, fuse connectors etc that were larger than the losses in the MOSFETS!? ?
?
That was very nice of you to do that search and point people to better choices!
Thanks,
Gordon Gibby KX4Z
|
Bill, The code is already integrated. Bob, Goody and I are changing the plumbing a bit before we add more modes. FreeDV, js8call and FT4 are at the top of the list. I would also love to do NBFM and AM
On Tue, Sep 6, 2022, 8:59 PM bill steffey NY9H < Ny9h@...> wrote: Has there been conversation or mention of FT4 inclusion into Sbitx.
So much faster and probably cooler on the finals .....
bill NY9H
|
Has there been conversation or mention of FT4 inclusion into Sbitx.
So much faster and probably cooler on the finals .....
bill NY9H
|
I'm curious if a switch could be added to this circuit to turn it on and off? Or better still, could it be controlled via 3.3v or 5v logic with a few extra parts?
I need an electronic switch and the added protection sure would be nice. Add in a 1.5KE15A 15-volt
transient suppressor diode and a fuse and you have over voltage protection as well.?
Max KG4PID
On Sunday, September 4, 2022, 04:45:54 PM CDT, Gordon Gibby <docvacuumtubes@...> wrote:
In our neck of the words, if a radio is important to us we build a polarity protector that connects directly to it. ?No battery or anything is allowed to connect direct again, must go through our polarity protector
On Sep 4, 2022, at 17:24, otalado <s53c.lado@...> wrote:
?You are doing a great job with the manual!!
btw: I am afraid this is a little bit off-topic: I saw your warning on the power supply plug polarity. Wouldn't it be a good idea, to place a Schottky diode into the rig itself? Ever since I lent one piece of relatively expensive equipment that returned to me burnt beyond repair, I am always making supply cables with such protection. This is until some 'clever' guy will try to use his own wrongly wired cable. So the protection in the box itself will make better sense.
Now in this 'prerelease' period dangers are perhaps low, but as less routined hams will come that will change, I'm afraid ...
|
One of the simplest ONE component protection is a Polarized
Relay.
All the rigs I tinkered with in the 80-90s had a polarized relay
on the TX final board.
Raj
On 06/09/2022 2:07 PM, Gordon Gibby
wrote:
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That's FANTASTIC of you, Jerry.? ?Much slicker
with the online stores than I had been.? ?
I ordered 8 of the IPP80 version just to have a
few more around the house since there are hundreds of them --
BUT THEY WONT LAST LONG FOLKS!!
I also updated the Construction Manual with the
availability information, giving the link to the available
part.??
See:???
?(now updated with a through-hole? part from your list)?
Using the lowest possible Rds-on just makes this
so so much easier on the builder.? ?The losses in our existing
units through the MOSFETS are actually lower than through the
crimped connectors etc in our powerpath.? ?I actually measured
losses in fuses, fuse connectors etc that were larger than the
losses in the MOSFETS!? ?
That was very nice of you to do that search and
point people to better choices!
Thanks,
Gordon Gibby KX4Z
Here's a quick search on Mouser for an enhancement mode
PFET with an Rds of 5 mOhms or less and a continuous drain
current of 50 Amps, must be in stock:
A couple TO-220 parts, either would work:
A bunch of surface mount parts with a big heat dissipation
pad on the bottom.
Those are usable for the hobbyist with a heat gun and some
solder paste.
Or could dead bug them, run a strip of copper over the top
for heat dissipation.
Jerry, KE7ER
On Mon, Sep 5, 2022 at 05:31 PM, Gordon Gibby wrote:
Irf4905 @ .020 ohms —. Put two of those in
parallel and you’ll get .010 ohms which means you can run 10
A through it and have a dissipation of only one watt. ?
?
Hopefully once people start returning our economies to
normal, better and better MOSFETs will become once again
available. ??
?
Right now it’s a bit difficult.? I’m sure Ashhar had to
deal with a lot of these problems!!
|
That's FANTASTIC of you, Jerry.? ?Much slicker with the online stores than I had been.? ? I ordered 8 of the IPP80 version just to have a few more around the house since there are hundreds of them -- BUT THEY WONT LAST LONG FOLKS!! I also updated the Construction Manual with the availability information, giving the link to the available part.?? See:??? ?(now updated with a through-hole? part from your list)?
Using the lowest possible Rds-on just makes this so so much easier on the builder.? ?The losses in our existing units through the MOSFETS are actually lower than through the crimped connectors etc in our powerpath.? ?I actually measured losses in fuses, fuse connectors etc that were larger than the losses in the MOSFETS!? ?
That was very nice of you to do that search and point people to better choices! Thanks, Gordon Gibby KX4Z
Here's a quick search on Mouser for an enhancement mode PFET with an Rds of 5 mOhms or less and a continuous drain current of 50 Amps, must be in stock:
A couple TO-220 parts, either would work:
A bunch of surface mount parts with a big heat dissipation pad on the bottom.
Those are usable for the hobbyist with a heat gun and some solder paste.
Or could dead bug them, run a strip of copper over the top for heat dissipation.
Jerry, KE7ER
On Mon, Sep 5, 2022 at 05:31 PM, Gordon Gibby wrote:
Irf4905 @ .020 ohms —. Put two of those in parallel and you’ll get .010 ohms which means you can run 10 A through it and have a dissipation of only one watt. ?
?
Hopefully once people start returning our economies to normal, better and better MOSFETs will become once again available. ??
?
Right now it’s a bit difficult.? I’m sure Ashhar had to deal with a lot of these problems!!
?
|
Re: DAYLIGHT ANALOG RADIO - 5MHZ WWV INTERFERENCE
Dave, Congratulations on the build! You can also move the IF to 4.915 MHz. It makes the frequency display a little more complicated but it is always a good idea to have an IF unlit by any of the standard frequencies.
On Tue, Sep 6, 2022, 10:20 AM David R. Hassall WA5DJJ < dhassall@...> wrote:
Dear Members,
I just finished wiring up my receiver modules and taking care of
this and that? when you first light of any home brew project.? Us
Amateurs on this side of the earth have the US National Bureau of
Standards Radio stations on 2.5MHz, 5MHz, 10MHz, and 20MHz
blasting out time and information signals 24/7.?? When I lit off
my DAYLIGHT ANALOG radio and was tuning around I had a beat note
in my receive audio.? Sure enough the 5MHz WWV time signals were
sneaking through my 7MHz Band Pass filter, through the first
mixer, crystal filter and beating against the BFO oscillators
signal in the 2nd Mixer.?? The Cure is simple.? A 5MHz trap made
from a T50-2 core with 32turns of #26 wire and put in series with
a 250pf of capacitance. (I used an old compression trimmer from my
junk box but the needed capacitance is somewhere between 220pf and
250pf to suck the 5MHz signal out.?? Now my DAYLIGHT ANALOG
receiver can listen to 40M SSB DX from Central and South America,
FT8 tones, and some really good clear CW.?? The only think to note
is that Experimental Methods in RF Design on page 5-12 recommends
that the PTO and the BFO signals be about 5V Pk to PK.? My PTO was
much lower than that and I have changed the 78L05 voltage
regulator to a 78L09 and my PTO signal is not quite 5V PK to PK
but the received signals have improved.? So, I believe that is
worthwhile doing.
For those who are curious what the 5MHz trap looks like in
reality, Here is a picture of mine.? (It is not the gold standard,
but it did work very well)
Keep at it.?? This radio is well worth the effort to collect all
the parts and build it.?? It will teach you many things and not
just the stuff that comes out of a book (but the book helps....hi
hi)
Take care and have fun.?
73 Dave WA5DJJ
SUPER QRSS/WSPR GRABBER:
--
73 Dave WA5DJJ
SUPER GRABBER
WEBSITE:
EMAIL: dhassall@...
|
DAYLIGHT ANALOG RADIO - 5MHZ WWV INTERFERENCE
Dear Members,
I just finished wiring up my receiver modules and taking care of
this and that? when you first light of any home brew project.? Us
Amateurs on this side of the earth have the US National Bureau of
Standards Radio stations on 2.5MHz, 5MHz, 10MHz, and 20MHz
blasting out time and information signals 24/7.?? When I lit off
my DAYLIGHT ANALOG radio and was tuning around I had a beat note
in my receive audio.? Sure enough the 5MHz WWV time signals were
sneaking through my 7MHz Band Pass filter, through the first
mixer, crystal filter and beating against the BFO oscillators
signal in the 2nd Mixer.?? The Cure is simple.? A 5MHz trap made
from a T50-2 core with 32turns of #26 wire and put in series with
a 250pf of capacitance. (I used an old compression trimmer from my
junk box but the needed capacitance is somewhere between 220pf and
250pf to suck the 5MHz signal out.?? Now my DAYLIGHT ANALOG
receiver can listen to 40M SSB DX from Central and South America,
FT8 tones, and some really good clear CW.?? The only think to note
is that Experimental Methods in RF Design on page 5-12 recommends
that the PTO and the BFO signals be about 5V Pk to PK.? My PTO was
much lower than that and I have changed the 78L05 voltage
regulator to a 78L09 and my PTO signal is not quite 5V PK to PK
but the received signals have improved.? So, I believe that is
worthwhile doing.
For those who are curious what the 5MHz trap looks like in
reality, Here is a picture of mine.? (It is not the gold standard,
but it did work very well)
Keep at it.?? This radio is well worth the effort to collect all
the parts and build it.?? It will teach you many things and not
just the stuff that comes out of a book (but the book helps....hi
hi)
Take care and have fun.?
73 Dave WA5DJJ
SUPER QRSS/WSPR GRABBER:
--
73 Dave WA5DJJ
SUPER GRABBER
WEBSITE:
EMAIL: dhassall@...
|
Right now this is intended just to view all the settings. ?I think Ashhar has some ideas for implementing a settings load function which would enable profiles.
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interesting? "\settings" - so in the future you could save those settings to a file and implement a settings load function to use them as saved profiles? On Mon, Sep 5, 2022 at 10:09 PM Ashhar Farhan < farhanbox@...> wrote: The \settings can just loop through all the controls.?
In my latest commit here:
- The center frequency of the spectrum display can be dragged using the mouse (or your finger on the touch screen) in the frequency strip below the spectrum grid.? This took me quite awhile to figure out how to code lol.
- The pitch line is centered on zero for only USB and LSB, all other modes it reflects the PITCH control
- The \sfs (spectrum frequency style) command I created earlier has been replaced by spectrum display frequencies that change format automatically based on the SPAN
- Spectrum display right-click QSY was introduced in an earlier commit, however I’d strongly encourage you to check it out if you haven’t already :-)
- The mouse pointer, reverse scrolling, and tuning acceleration commands have changed slightly; check out \h2 (help page two) for details
- I’ve started a settings command to see current settings (\s or \settings).? It’s a work in progress.
73 Goody K3NG
|
Indeed. ?I will work on that.
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The \settings can just loop through all the controls.? In my latest commit here:
- The center frequency of the spectrum display can be dragged using the mouse (or your finger on the touch screen) in the frequency strip below the spectrum grid.? This took me quite awhile to figure out how to code lol.
- The pitch line is centered on zero for only USB and LSB, all other modes it reflects the PITCH control
- The \sfs (spectrum frequency style) command I created earlier has been replaced by spectrum display frequencies that change format automatically based on the SPAN
- Spectrum display right-click QSY was introduced in an earlier commit, however I’d strongly encourage you to check it out if you haven’t already :-)
- The mouse pointer, reverse scrolling, and tuning acceleration commands have changed slightly; check out \h2 (help page two) for details
- I’ve started a settings command to see current settings (\s or \settings).? It’s a work in progress.
73 Goody K3NG
|
interesting? "\settings" - so in the future you could save those settings to a file and implement a settings load function to use them as saved profiles?
On Mon, Sep 5, 2022 at 10:09 PM Ashhar Farhan < farhanbox@...> wrote: The \settings can just loop through all the controls.?
In my latest commit here:
- The center frequency of the spectrum display can be dragged using the mouse (or your finger on the touch screen) in the frequency strip below the spectrum grid.? This took me quite awhile to figure out how to code lol.
- The pitch line is centered on zero for only USB and LSB, all other modes it reflects the PITCH control
- The \sfs (spectrum frequency style) command I created earlier has been replaced by spectrum display frequencies that change format automatically based on the SPAN
- Spectrum display right-click QSY was introduced in an earlier commit, however I’d strongly encourage you to check it out if you haven’t already :-)
- The mouse pointer, reverse scrolling, and tuning acceleration commands have changed slightly; check out \h2 (help page two) for details
- I’ve started a settings command to see current settings (\s or \settings).? It’s a work in progress.
73 Goody K3NG
|
The \settings can just loop through all the controls.?
In my latest commit here:
- The center frequency of the spectrum display can be dragged using the mouse (or your finger on the touch screen) in the frequency strip below the spectrum grid.? This took me quite awhile to figure out how to code lol.
- The pitch line is centered on zero for only USB and LSB, all other modes it reflects the PITCH control
- The \sfs (spectrum frequency style) command I created earlier has been replaced by spectrum display frequencies that change format automatically based on the SPAN
- Spectrum display right-click QSY was introduced in an earlier commit, however I’d strongly encourage you to check it out if you haven’t already :-)
- The mouse pointer, reverse scrolling, and tuning acceleration commands have changed slightly; check out \h2 (help page two) for details
- I’ve started a settings command to see current settings (\s or \settings).? It’s a work in progress.
73 Goody K3NG
|
In my latest commit here:
- The center frequency of the spectrum display can be dragged using the mouse (or your finger on the touch screen) in the frequency strip below the spectrum grid. ?This took me quite awhile to figure out how to code lol.
- The pitch line is centered on zero for only USB and LSB, all other modes it reflects the PITCH control
- The \sfs (spectrum frequency style) command I created earlier has been replaced by spectrum display frequencies that change format automatically based on the SPAN
- Spectrum display right-click QSY was introduced in an earlier commit, however I’d strongly encourage you to check it out if you haven’t already :-)
- The mouse pointer, reverse scrolling, and tuning acceleration commands have changed slightly; check out \h2 (help page two) for details
- I’ve started a settings command to see current settings (\s or \settings). ?It’s a work in progress.
73 Goody K3NG
|
Re: #sbitx A cool (kludgy) way to remotely use the sbitx
#sBitx
John,
I do not know the rationale behind needing a full Linux on a Windows PC to run an X-Windows server.? Before finding the VNC option on Raspian (one of the official Raspberry Pi OSes), I used Xming with SSH.? Here is the webpage for Xming:
I do not have it on my PC anymore, as VNC handles all of what I have wanted.? I remember I used Putty to start an SSH and then started Xming from it.
Unless there are reasons for having an actual X-Windows environment, VNC meets most needs.
73
Evan
AC9TU
|
Re: sBitx regulator upgrade info/help with problem
#sBitx
I see you sensibly did a bulk shipment to the USA and then had them posted to individual addresses from there. Did they also get posted to non-US purchasers?
Bill VK7MX
|
Here's a quick search on Mouser for an enhancement mode PFET with an Rds of 5 mOhms or less and a continuous drain current of 50 Amps, must be in stock:
A couple TO-220 parts, either would work:
A bunch of surface mount parts with a big heat dissipation pad on the bottom.
Those are usable for the hobbyist with a heat gun and some solder paste.
Or could dead bug them, run a strip of copper over the top for heat dissipation.
Jerry, KE7ER
On Mon, Sep 5, 2022 at 05:31 PM, Gordon Gibby wrote:
Irf4905 @ .020 ohms —. Put two of those in parallel and you’ll get .010 ohms which means you can run 10 A through it and have a dissipation of only one watt. ?
?
Hopefully once people start returning our economies to normal, better and better MOSFETs will become once again available. ??
?
Right now it’s a bit difficult. ?I’m sure Ashhar had to deal with a lot of these problems!!
?
|
Irf4905 @ .020 ohms —. Put two of those in parallel and you’ll get .010 ohms which means you can run 10 A through it and have a dissipation of only one watt. ?
Hopefully once people start returning our economies to normal, better and better MOSFETs will become once again available. ??
Right now it’s a bit difficult. ?I’m sure Ashhar had to deal with a lot of these problems!!
toggle quoted message
Show quoted text
On Sep 5, 2022, at 19:22, JerryP <jponko@...> wrote:
? You could also try the IRF4905 MOSFET P-Channel 55V 74A @$1.50 each which is 0.020 Ohms. The same one used to power the SBITX RF power amp.
On Mon, Sep 5, 2022 at 5:27 PM Shirley Dulcey KE1L < mark@...> wrote: Although those Nanos are no-name clones, the key component on them is normally a real Atmel microcontroller. I gather that some clones of the Atmel chip have started to appear; those should be avoided. Every?Nano clone I have bought has an actual Atmel chip. The Arduino designs are open source hardware, and the bootloader is open source software, so clones are completely legal.
The Nano clones use an inexpensive USB to serial chip from China (originally a CH340G; they have now shifted to a CH340C, which is even cheaper because it has a stable onboard frequency reference and does not require a crystal) rather than the FTDI chip used on a real Nano, but that does not affect their operation in ham applications. (You may have to do the extra step of installing a driver on Windows systems the?first time you connect one.) The FTDI chips are stupidly expensive; the Arduino Uno uses a second Atmel microcontroller just for USB-serial conversion because it's cheaper than the dedicated FTDI chip!
Tayda looks like a good steer for a cheap PFET.
But be aware that the on resistance of an IRF5305 is 60 milli-Ohms, which is 20 times more than the part Gordon was working with.
So if your rig draws 10 Amps there will be a 10*0.060=0.6 volt drop across this PFET, and you may as well just use a big Schottky diode in series.
Also, IR/Infineon consider this part to be obsolete, so now only made by no-name second tier clone manufacturers.
For example, these guys list the manufacturer as "various".
Not necessarily a bad thing, there are thousands of uBitx's out there with a clone no-name Nano,
and the Nano is far more complicated than a PFET.
I've bought a bunch of stuff from Tayda at their alarmingly low prices, it all seems to work just fine.
Jerry, KE7ER
On Mon, Sep 5, 2022 at 11:41 AM, JerryP wrote:
If you're looking for a P-Channel MOSFET for a power switch then this may be able to use a IRF5305 - TO-220, 55V, 31A, 0.06Ohm RDS On @$0.78 each:
Tayda has a $5.00 minimum order and their USPS shipment is 8-16 days and low cost.? While they may not have everything, it's very low priced and good quality.
?
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--
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Raj vu2zap
