Replacing memory back up cells with a super capacitor
We were discussing batteries a few weeks ago and I mentioned I used high value capacitors, AKA super capacitors, to replace the 3V lithium disk cell.
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I received an email asking for details.
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All of the receivers have a 5V rail, I used a 4 1N914 or 1n4148 small signal silicon diodes between the 5V rail and positive of the super capacitor to drop the voltage. The nominal voltage drop of a silicon diode is 0.7V, however under extremely low current this can drop to as low as 0.5V. It will vary from diode to diode even in the same family.
I also included a 100 ohm resistor just in case, I like to always have current limiting.
The V+ of the super capacitor was connected directly to the V+ memory backup.
In my first installation I did things a bit different. I used a 1K resistor from V+ 5V to a string of 1n4148 diodes to give a "regulated" V+ between 2.5V to 2.9V. Memory keep alive in the R-2000 is 2V.
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I adopted the first version I described after some thought and experimentation with a R-2000 with a defective tuner optical pulse decoder on the main PCB that defied repair.
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You can tune the radio, it's just a royal PITA that can take an hour to tune to the desired frequency. I programmed in useful frequencies in all 10 channels and treat the radio as a fix tuned radio. I have WWV on 2.5/5/10/15, CHU on 7.850, and, US Global HF Network 4.7240, 8992.0 11.1750, 15.0160 and 11.2320 [interoperations with Canadian forces].
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My super capacitors came from the factory keep alive PCB in Kenwood commercial radios, these PCBs were removed and trash after the PCB with all the programmed channels was installed.
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I've modified 10 Kenwood R-2000 general coverage receivers and 2 iCom IC-28A 2M amateur transceivers. I'll be modifying 3 more IC-28A in the near future.
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My super capacitors are 30 years old and are 4.?F, One R-2000 was not powered up for at least 4 years, probably 5 and half, all the memory channels were still there.
Modern higher value super capacitors might have higher internal leakage. I've ordered some 100F 3V supercaps to experiment with.
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Supercapacitors have odd chemistry and I suspect they will last longer if they are kept biased at their operating voltage. I was given about 30 of the Kenwood keep alive boards, pulled the supercapacitors and they are on a 3V rail powered by my primary 12V ham radio power rail.
They've probably been without power for maybe a week since I wired them to the 3V rail.
My experience with the R-2000 that was powered off for at least 4 years suggests the chemistry is more robust then I initially suspected, but, the supercapacitors are in a dedicated plastic box and I see no reason to remove them from the power. [I'm too lazy to change some things without a good reason.]
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All of this came about because I couldn't find a replacement battery in Lexington and didn't want to wait for mail order, well that plus the memory back up cell in the R-2000 is soldered in, which means you have to remove all the very flimsy (cheap) connectors.
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I was initially going to mount a 2 AA battery holder on the rear of the R-2000 when I was given the Kenwood "keep alive" PCBs and decided to give a crazy idea a try.
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YMMV
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How do you measure really high voltage...like for a spark plug.
I ran into a problem Monday, time for the first lawn cutting of the year, trust me, at 73 I don't even use a riding mower because the vibration would kill my artificial knees, our landlords are a set of identical twins who love yardwork (as far as I'm concerned you could cover the front and back yards out to 50 feet from our home with a foot of small gravel and spray with an herbicide at regular intervals.)
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I did all the normal checks. The fuel was drained at the end of the season, from the fuel tank and carburetor bowl, the engine ran with fogging oil and the air filter cleaned, then the riding mower was placed in the detached garage.
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For the new season, the tires were checked and topped off, a new spark plug was installed, good gas used to fill the tank.
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The battery was on a float charger all winter.
Turning the key to start caused the starter to crank with normal speed but no joy, not even a backfire. I used some ether (I'm lazy) and got a feeble backfire.
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Testing with a spark plug showed an arc the gap, but, at peak compression it takes a lot more voltage for the arc to form, how much more voltage, I'm not sure. But a mechanic told me "Up to 4 times."
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OK how on earth do I measure up to 20kV?
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The Leslie Corporation offers a nifty inline tester with a neon bulb with terminals on each end. The tester goes in series between the ignition coil output and spark plug hot terminal. If good, as in adequate, high voltage is present, the neon bulb will flash pretty brilliantly, if the high voltage is low, there might be a dim glow. The Leslie
20610 INLINE SPARK TESTER is available at Advance Auto or online. I went with Advance Auto because we decided time was more valuable then a few dollars.
It was money well spent.
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Changed the ignition coil, PITA to get to, and presto, our landlords think I'm a genius. [Ha do I have them fooled or what?]
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We also used compressed air to blow debris out of the ventilation fins on the flywheel and generally clean the engine.
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The engine started instantly and ran perfectly. Looking back it is clear the ignition coil was dying over the last 2 or 3 summers because the engine runs smoother with a LOT more power.
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Our next joyful task will be to change the drive belts. They are a little frayed and I feel it's a lot better to change them when it's 50 then 90 with 80% RH. [Yippee I can't wait.]
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Re: logic of bjt regulator
On Sat, Mar 15, 2025 at 05:00 AM, john23 wrote:
Could you describe how the regulating dinamics works here?
Pull out your analog design books.
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This is a feedback loop.? The two NPN transistors are a differential pair.? ?I trust you know how differential pairs work.? The difference voltage between the two bases drive the collector currents, and thus, the voltage on node 1.
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The PNP transistor further amplifies the voltage on node 1.? When that voltage drops lower than +14.3V, the PNP turns "on" harder and passes more collector current towards the load.
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In operation, it is a feedback circuit that drives the output (node 3) until it roughly equals the voltage at the left NPN's base.? If it drops below +2 V, the left NPN conducts more collector current, node 1's voltage falls, the PNP turns "ON" harder, and sends more current to the load - as needed, to pull that voltage back up.? Hence, it regulates it at about +2 V.
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Andy
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Hello, I am trying to understand the dinamics of the circuit taken from the youtube video.
if we apply 2V DC the node 2 on the photo will be 1.4 (Vbe=0.6)
The node 1 will expirience some voltage wich will be translated to the other PNP base.
Could you describe how the regulating dinamics works here?
Thanks.
https://www.youtube.com/watch?v=nOOOAjoqCt8&list=PL4C141B35706AD19A&index=3
/g/electronics101/photo/296358/3896088?p=Created%2C%2C%2C20%2C2%2C0%2C0
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Re: A downright amazingly stupid LED headlight, I'm impressed.
On Fri, Feb 28, 2025 at 11:35 AM, wn4isx wrote this about motorcycles:
They still don't see you, even at night with your headlight on drivers will cut you off with frightening regularity.
I have a theory about that.? Drivers instinctively use the space between oncoming headlights to gauge how far away it is.? Motorcycle headlights lack that clue.? So the auto driver thinks it is very far away and there is plenty of space to turn.
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Headlamp brightness probably would not help.? It still looks far away.
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In daylight, I suspect many auto drivers (instinctively?) think motorcycles can't be as fast as or faster than their auto, so certainly there must be plenty of time.? ?Even if the motorcycle gets cut off, they are small and can stop fast - right?? The driver might not THINK this, but it is what their brains are telling them.
I think auto drivers do not purposely try to get in the way of motorcycles.? We all know they are death traps, a surely unsafe way to go down the highway, so why would anyone want to make it even less safe for them?
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I lost a cousin just a few years ago, riding his motorcycle home from work.? The intersection where it happened has claimed the lives of several unfortunate souls, yet the city stupidly does nothing to improve it - even when senseless accidents like that happen again and again.? They probably say it is too expensive to mark it better.? Shows you how little they value a person's life.
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Andy
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Re: analog feedback temprature regulator question
This is just a question about the question you asked, as I am unable to provide information about plans for a differential temperature regulator -
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On Thu, Mar 13, 2025 at 06:11 AM, john23 wrote:
Hello, I am looking for a differential feedback temprature regulator project which explains the theory best it could and give practical example in simulation.
I am looking to design a very precise temprature regultor up to 1Kelvin.
I am unsure how to interpret "1Kelvin".
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Do you mean that the device should continue to work down to a minimum temperature of 1 K (1Kelvin)?
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Or do you mean that the device's precision should be 1 K?? If this is what you meant, then I think 1°C is an equivalent amount of precision, because a temperature change of 1°C and 1 K are equivalent.? Do you agree?
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Andy
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analog feedback temprature regulator question
Hello, I am looking for a differential feedback temprature regulator project which explains the theory best it could and give practical example in simulation.
I am looking to design a very precise temprature regultor up to 1Kelvin.
Is there some material of a project I could try to learn it?
Thanks.
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Another extensive active antenna link!? Thanks! More reading ? Time allowing, I will build something. ???Right now, I got to take care of business as a priority so getting something that reasonably works is way to quickly fire up the SDR. For $12 arriving in two days looks like a good choice.? Being open, it allows me to see the design.? I obviously need to add a simple enclosure. I have lightning rods on my home, so I plan to attach the antenna to one of them.? I will ground the bottom end of the coax to the buried ground system. That reminds me:? When I built the house, I used 1” regular copper plumbing to run a low impedance ground connection from buried lightning ground system to my workbench. The plumbing inspector had a fit since the pipes were not on the plumbing drawings. Bertho ?
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From: [email protected] <[email protected]> On Behalf Of wn4isx via groups.io
Sent: 9 March, 2025 12:56
To: [email protected]
Subject: Re: [electronics101] Active Antennas? While I learned the required subject mator for my two degrees in university, the main thing I learned in university was how to research. It was a bit of a challenge to transition to the web but well worth it it. At my last two jobs I was the unofficial "researcher." I'd seriously consider breadboarding a stock PA0RDT dead bug style, isolate the 'plate' with a dremal tool. The J310 is easy to locate, the 2N5109 might be a challenge. Avoid active antenna designs with MOSFETs as the gate capacitance will kill the incoming RF. This can be avoided but it gets way too complex for the performance of the antenna. This is another resource, I've built the antennas using 6CW4, I used 13CW4 because I had them. This design works extremely well...OK can't copy the link as it brings up the graphic. Look for the design that uses 3 6CW4s.
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While I learned the required subject mator for my two degrees in university, the main thing I learned in university was how to research. It was a bit of a challenge to transition to the web but well worth it it.
At my last two jobs I was the unofficial "researcher."
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Glad to help.
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I'd seriously consider breadboarding a stock PA0RDT dead bug style, isolate the 'plate' with a dremal tool.
The J310 is easy to locate, the 2N5109 might be a challenge.
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Avoid active antenna designs with MOSFETs as the gate capacitance will kill the incoming RF.
This can be avoided but it gets way too complex for the performance of the antenna.
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This is another resource, I've built the antennas using 6CW4, I used 13CW4 because I had them.
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This design works extremely well...OK can't copy the link as it brings up the graphic.
Look for the design that uses 3 6CW4s.
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Thank you wn4isx! Your link to Martin G8JNJ’s active antenna pdf very extensive: ?
More reading……. I saw the other two links on the mini-whip. Bertho
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I found that one, , ?but I have not found the second part one in the pictures that is discussed with improvements. I found this one that looks promising:
Bertho ?
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From: [email protected] <[email protected]> On Behalf Of wn4isx via groups.io
Sent: 9 March, 2025 11:03
To: [email protected]
Subject: Re: [electronics101] Active Antennas? Pedid y recibiréis ? Simple and better circuit for MiniWhip antennas
? The 2SC5551A might be a viable substitute for the 2N5109 in the original PA0RDT Mini-Whip. It has a lower Ic but better Ft. This is one of my way too many projects that I might get around to before I run out of time on this side of the grass. ?
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After spending too much time searching and reading about active antennas and building a library, I visited Amazon. Search for “Mini-Whip Antenna”. There are enclosed ones, but I ordered a promising looking open one for $12 to play with before building or getting a permanent one. Bertho
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Re: Some comments on SDR radios and control software
Pieter-Tjerk de Boer, PA3FWM? has a series of articles on E-Field antennas that can be extremely helpful in getting the best performance from these antennas.
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Fundamentals of the MiniWhip antenna
https://www.pa3fwm.nl/technotes/tn07.html
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Grounding of MiniWhip and other active whip antennas
https://www.pa3fwm.nl/technotes/tn09d.html
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[Note it is critical to properly ground the E-Field antenna at the antenna and to isolate the coaxial cable feedline from EMI generated within your home!]
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Simple and better circuit for MiniWhip antennas
https://www.pa3fwm.nl/projects/miniwhip/
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Martin G8JNJ had a very informative web page on active antennas. His use of high inductance RF chokes in the feedline is an extremely useful technique to isolate the ative antenna from EMI generated in the home. Sadly his webpage has vanished but a PDF capture of the webpage can be found at
https://qsl.net/l/lw7dfm/Antenas/Antena%20Mini%20Whip/MARTIN%20-%20G8JNJ%20-%20Active%20antennas.pdf
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His webpage is archived on the "wayback machine" but it won't always load.
https://web.archive.org/web/20230722120107/https://www.g8jnj.net/activeantennas.htm
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I use quad shielded 75 ohm flooded coaxial cable to connect to my E-Field antennas. Assuming my Kenwood R-2000 receiver has an actual antenna input impedance of 50 ohms, exceptionally unlikely, the worst case VSWR would be 1.5:1.
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The SDRplay RSP-dx has a claimed input impedance of 50 ohms over it's entire operational range. I have no reason to doubt this but no way to verify it either. Reception was so similar with the 75 ohm and 50 ohm coaxial cable I couldn't tell any difference and 75 ohm flooded (rated for direct burial) cable is a lot easier for me to obtain here in central Kentucky. The son of a member of our shortwave listening club is an engineer for the local cable TV company and can divert reasonable lengths of coax. I also have 7/8 hardline for the two antennas located the farthest from our home.
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I just connected a Radio Shack Disk Cone antenna (at least 40 years old now) to my RSP-dx and I can receive all of the NOAA VHF WX stations within 150 miles. There are more commercial FM BCB stations then I can count and I can receive a 2M amateur repeater that I know runs 50W that is located just over 100 miles from my home. Constructing a decent disk cone isn't that challenging but Diamond and others offer them for reasonable prices, so it becomes, do I want to trade money for time.
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Pedid y recibiréis
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Simple and better circuit for MiniWhip antennas
https://www.pa3fwm.nl/projects/miniwhip/
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The 2SC5551A might be a viable substitute for the 2N5109 in the original PA0RDT Mini-Whip. It has a lower Ic but better Ft. This is one of my way too many projects that I might get around to before I run out of time on this side of the grass.
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Re: Some comments on SDR radios and control software
Thanks, I have no specific plans except testing the new technology and also look at GPS signals. I did a lot of work with GPS 30 years ago and I still have some active GPS antennas to try. The PAORDT type active antenna looks like a good general start. Bertho ?
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From: [email protected] <[email protected]> On Behalf Of wn4isx via groups.io
Sent: 8 March, 2025 22:00
To: [email protected]
Subject: Re: [electronics101] Some comments on SDR radios and control software? What do you want to listen to? I might be able to offer some advice.
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Previously wn4isx posted a link to: The reference refers to an improved version but there is no link to it. Does anyone know where I can find the improved version schematic? Any other suggestions? I remember seeing an article about installing an active antenna and avoiding extra local noise, but I do not remember where I saw it. Using SMT components is not a problem. Thanks Bertho ?
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Re: Some comments on SDR radios and control software
What do you want to listen to?
I might be able to offer some advice.
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Re: Sata acquisition and data logging
As I mentioned, I have one main program that was extremely expensive, cost me over $1000, I also routinely use Adobe Audition, while there are good audio programs for Linux like Audacity, they are not nearly as powerful or flexible as Audition. Until and unless I can get those programs to work under Linux, I'm stuck with Windoze.?
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Re: Sata acquisition and data logging
Yes but I'd be forced to learn to use an Ardino, build a case, etc, the Dataq requies a USB cable and is ready to go, time saved at my age is well worth a few dollars.
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Re: Some comments on SDR radios and control software
Thanks for the introduction of SDRplay. I used to design commercial RF equipment but not for the last couple of decades. So I decided to buy the SDRply RSPdx-R2. Now I have to review the antenna options. Bertho ? From: [email protected] <[email protected]> On Behalf Of wn4isx via groups.io
OK I am not pushing the SDRplay line of SDR (software defined radios) but I received a PM that prompted this post. Oh I?have no relationship with SDRplay then as a generally satisfied customer. ? I've owned several SDRplays and found then all adequate for general shortwave listening with the added benefit of reception up to 2GHz. ? There are people using SDRplay RSPxx receivers for police scanners, listening to aviation, listening to satellites, all sorts of VHF/UHF reception. ? I can't speak to VHF/UHF reception because I gave up listening to police and fire when they went to APCO25 digital. ? There are ways to receive APCO25 with the SDRplay RSPxx series, but, reading the "how to" it felt like a lot more trouble than it was worth to me. ? SDRplay bought the rights to a SDR control program and have made upgrades over the last decade or so to improve performance and to interface other software.
? Recently they offered a new program developed in house that offers vastly improved performance.
? From my perspective the fact this software only operates on Window 10/11 and that was a deal killer.
? However this program also supports the Raspberry Pi4, Pi5.
? Now I don't know anything about Raspberry or Linux but a friend's daughter does, she makes embedded control systems and this was a 10 minute project for her. ? My Raspberry Pi 5 is in a forced ventilation case. It supports a nice LCD screen, keyboard, mouse, and remote access/control via Ethernet. ? I use the RSPdx for MW DXing. ? I also use the RSP-1a as a panoramic adaptor, 'spectrum analyzer', for use with my tricked out Kenwood R-2000. I use the older SDRuno with a Windows 7 64 bit professional computer that also runs audio analytic software to figure out data formats. I also use a hardware FSK demodulator to drive software decoders that another friend wrote. [sorry he plans to sell them, so I can't share copies.] ? Sidebar as they said in the O.J. trial. I've been into shortwave listening since I was 12. I saw my first panoramic adaptor later that summer at the ham shack of a friend of my father and fell in love with the idea you could see RF on either side of where you were tuned. It took about a minute to realize I could ID SSB, CW, AM voice or music, and FSK. I barely understood FSK but the waveform was crystal clear on a spectral display. It only took 50ish years to have a spectral display. ? ? NOTE: While I've found the RSP family suitable for my needs, others may find them lacking. I strongly suggest anyone ready to dip their toes in the world of SDR to do their research. SDRs range from simple USB thumb drive sized units, with what might be considered marginal performance to SDRs like the Perseus or WinRadio, both offer world class performance with different approaches. ? I've played with both and both are amazing radios and come at a premium price. I'd start with something more modest, SDRplay or Airspy are probably the best, decent, introductory SDRs. I have minimal experience, an afternoon, with an Airspy SDR, I wasn't overly impressed but the band could have been dead that day. It happens. ? NOTE 2: The thumb drive SDRs are considered little more then toys by many. I have zero experience with them so I don't have an opinion.
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Bertho