I use the 74LVC573, the 74LVC373 is the same device with a different pin out, they will handle faster switching signals than discrete FET based level shifters.
7:08: A voltage divider can get you in trouble in those cases where you should have made a buffer to the next section. The numbers shift in the next voltage divider (without a buffer), so to speak. Took me some time to figure that out.
This is correct, any load at the "output" of the divider is in parallel with the lower resistor and loads the divider. You can take that effect into account when designing the divider but I would advise against that and use a buffer in cases where you have a low impedance load. That buffer can do the level shifting by itself if selected properly...
Hello. Sorry for the late response. I have these tracked in a local git repo. I noticed that I never published them anywhere (I think, there used to be a yahoo group(?) but I can't remember if I uploaded some files there). Please note that since this was like 10 years ago, my files were created with what is now a very old version of kicad. I also never finished this project because of complicated reasons. All that said, I suggest that you look for more recent and complete versions of those PCBs. This used to be a popular project so they must exist. In case you don't find anything or if there are other reasons for you to have my files specifically, I'm happy to share -- just respond to this message and I publish them somehow.
The SBH-52 that replaced the CD-41 is a different layout. It has an eFuse in an 8 pic SOIC package, and I don’t believe any FET pin is directly connected to the middle terminal.
The proper way to place your TVS diode is right at the input terminal. That means at the entry point where the signal comes from the outside world. The reason is because you want to shunt the high voltage as early as possible, that is before it gets into your circuit. If you let severe ESD HV spikes into circuit it will wreak havoc many other components along the trace it came in. It may also induce secondary electro static discharge and severe electromagnetic interference to traces nearby the traces, exposed copper, and exposed pins that it came in too. If you put the TVS diode just before the 100k Ohm resistor, you could have solved all the headache you had been through. I believe D2 is the Zener diode. If this is the case, it is probably enough to protect the Source of the PMOS. If you are concern, you can put another 12V bidirectional TVS diode before the R1 (1k).
AND WHY DON'T YOU BETTER CONFIGURE YOUR ARDUINO PIN AS INPUT, AND PUT IN IT, FOR EXAMPLE, A 4.7K RESISTOR, AND WHEN YOU WANT A ZERO YOU SIMPLY CONFIGURE IT AS OUTPUT AND SEND A ZERO.
This is essentially the open drain approch, just with a microcontroller. What I discuss in the video, however, does not presume the presence of a microcontroller. Also, keep in mind that according to the datasheet of the microcontroller used on any arduino board, there is a maximum input pin voltage that you are not supposed to exceed. This is usually a little bit above the supply voltage. Following your suggestion for a down-shifting converter would violate that spec and the internal protection diode would start conducting. The series resistor would limit the current and probably prevent damage, but it would also limit the rate at which you can toggle the pin, as discussed in the video. I would advise against this technique unless you are down-shifting or have checked that you are not in violation of the the spec.
I figured out who you sound like. Look up superfluid helium. There is a physics guy from the 60's named Alfred Leitner who produced a series of videos on this phenomena.
hello, I ran into a situation, I need a DDS frequency synthesizer, I made it on plis. frequencies are needed 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 MHz. I chose a clock frequency of 250 MHz, everything seems to be fine, I removed large aliasings, they appeared after 60 MHz, but I still have small components of the spectrum at frequencies of 15, 20, 25, 30 and so on. I don't understand how to remove them. let's say I choose the desired frequency of 20 MHz, and put the filter on, then everything is fine, but if I need to switch to a frequency of 30 MHz, then there will be no spectrum, since the filter is currently working. how to be in such a situation?
well done, alot of meat and direct (as opposed to most current videos that seem more focused on editing and "side entertainment")....very dense but very useful video. A big thanks!
At 8:03 you're describing an "N-Channel Enhancement Mode Insulated Gate MOSFET". However, there are other MOSFETs called "N-Channel Depletion Mode Insulated Gate MOSFETs" that do conduct when the gate voltage is 0 volts and turn off at negative voltages. With Depletion mode you don't require a pullup to +3V. Just connect the gate to 0V or gnd. Hint, maybe +3V isn't readily available. You can also use "N-Channel Depletion Mode Junction FETs", (nearly all are) for this. redrok
I did this on my IC-7100. I didn't use a dongle but a SoftRock IF plugged into my Elecraft K3 for receive with HDSDR software. I also used the "Data In" pin on the mini-DIN connector with the rig set to "9600 baud" mode. It isn't 9600 at all but a wide bandwidth audio input without preemphasis or other equalization. The first thing I tried was setting the audio frequency to 1250 and increasing power gradually. Before I could see the null, the 7100 stopped transmitting due to excessive audio level, above the nominal 100-300mVp-p. The method I ended up using was to set the audio voltage to 300mVp-p and lower the frequency until I saw the null. That worked and showed the maximum deviation to be 1680Hz. Further lowering the frequency revealed a 2nd and third null, and by looking up those modulation indices in Wikipedia, determined that the resulting deviation estimate was very close to 1680Hz as well. I haven't tried the "1200 baud" port yet but it may well show that it is 3Khz. I think the deviation for 9600 is limited due to the bandwidth required to handle audio in the 3-6kHz range. Thanks again for your informative video.
Does anyone know how to update the firmware on this device? I tried following the recommended procedure and get a syntax error - apparently from the cyflash utility.
I just gave this a try for the giggles, and indeed cyflash throws a syntax error. At least in my case, this is because python has moved on and the syntax used in cyflash is not valid anymore. Ways to get around this could be (1) use python 2 if you have it (2) use cyflash from his git repo instead of installing with pip. Apparently he did a number of bugfixes specifically regarding python syntax compatibility, they are in the repo but not released, apparently (3) fix the syntax error. if you know python these are easy changes more often that not.. hope you get it sorted and good luck! Matt
@@MrCircuitMatt Thanks for the response. I have an email out to Nick Johnson (the developer) so, I’ll wait to see what he recommends (probably same as you!). Regards, Grant
At 16:20 you are adjusting the voltage while calling it out in kHz. The baseband frequency domain display is growing in amplitude but the frequency is constant. You switched back to volts once you get to the Bessel zero. I liked how you used GNU radio to put everything on one display. It's good for us hams who don't have those $20K mixed domain oscilloscopes with built in frequency analyzers.
The battery middle terminal is not a resistor or NTC. It is connected directly to the battery + terminal (resistance below 1 ohm). From the circuitry it looks like the middle terminal is only detecting that a battery is present if the middle terminal is connected to the + terminal, then giving some bias current to the Darlington transistor pair to start charging. I recently bought this charger and it is not broken. I just wanted to analyze it to see if it will break my battery and/or start a fire. It is really scary, there does not seem to be any battery temperature protection or battery over-voltage protection in the charger. I hope the battery has an internal one, it most likely has. The green led goes on only if the charging current goes to zero, while the middle terminal is still connected to the + terminal. At that point the voltage at the battery + terminal and middle terminal will be almost the input voltage (12V). Scary! The use of MOSFET and high resistances at the middle terminal is probably because the leakage current will be minimal if you leave the battery in the charger while it is not plugged in (to the 12-16V supply). Oh and by the way, the input over-voltage protection is insanely high. It kicks in maybe after 19V or so. (The zener is maybe 18V) So the 16-19V range is unprotected and forbidden.
Thank you... I cannot really check what's hooked to the middle terminal (always kind of suspected a thermal fuse there but I don't know). If any of the things you mention are true, though, that would be somewhat crazy by Yaesu. Sadly though I really wouldn't be surprised if that is exactly what they did... thanks for your comment!
Another Bummer is that the CD-41 will not function properly with the SAD-25 Charger supplied with the FT3D, although the CD-41 states that it will work from 10.5V (which the SAD-25 provides) ... It acutally won´t.... No green light will come on, and the battery never gets fully charged.
I am using The CD-41 with a wall P.S.12V 1000mA - I then ordered a genuine Yaesu SAD 11C, that is referenced for the USA market... whatever it means... (exactly the same as the SAD-25C -10.5V 1000mA) and it works like a champ with both.
3:27 yes , i guess you are talking about the problem of exporting the pcb file from express pcb ! because there is no pdf option . i also use this software for pcb but i use a trick to export its pcb file as pdf using primo pdf as printer sim
Absolutely OUTSTANDING!!!! Great troubleshooting and analysis. As soon as you drew the MOSFET. I thought ESD Zap! Thanks for a great video. Now I need to go fix mine...
Man, you should make this kind of video a lot. That's impressive. You are so clear and explain everything detailly. I need a mentor like you. One question: Is open-drain configuration bidirectional?
Hello and thank you. No the circuit I show is not bidirectional. If you need that, you could look at e.g. learn.sparkfun.com/tutorials/bi-directional-logic-level-converter-hookup-guide/all this circuit
@@MrCircuitMatt I ask that question for clarification. I saw same open drain configuration in that url. But it says that open drain configuration is bidirectional as I understand from that guide. learn.sparkfun.com/tutorials/bi-directional-logic-level-converter-hookup-guide/all
@@BiqBanq The circuit in that guide is bi-directional. I'm not sure I would call it "open-drain" but at the end of the day, the circuit in the guide is bi-directional and the circuit that I show in the beginning of the video is not. I do show the circuit from the guide at 5:00 in the video, though -- maybe that is the source of confusion. I had forgotten that I actually also discuss this circuit.
I am interested in fully understanding how everything works it's just I did not go to a university & I have not found anyone that explains Electronics to the detail that you do. I am self-taught with no mentor, assembling blocks of components of pre-assembled Electronics. I try to work with individual components when my knowledge allows me to.
I finally find a video that goes into great depths in explaining this and then I find out this video is 7 years old & this RU-vid creators last video was created four years ago! I guess he couldn't be bothered making videos anymore because he is busy with work? We need more people like him on here!
Thank you for this great video! Currently working on my first electronics project, and the Logic Level Converter I bought uses a MOSFET. I encountered some issues with SPI communication, and the oscilloscope part of the video helped me to understand and then solve the issue!
Extremely irritating that excellent RU-vidrs such as this MrCircuitMatt are dead. As though their mere purpose to appearing is to save humanity, and then magically vanish to quantum realm with their excruciating entanglement when their sole purpose of life is achieved.
I am not dead :-). I just had a difficult period in my life that made it hard for me to continue with the videos. That, or maybe my quantum state collapsed upon your observation haha
@@MrCircuitMatt Ah, there you are! Uhmm. I do not know what you are going through but I can relate and understand whatever that/those are. I have my own share of idiotic dramas that I never ask for, and that are beyond my control. Yes, the word 'dramas' with an arse. Because language is alive I say dramases, lots of arses.
Excellent analysis and repair - i am very impressed and would like to repair the one I have. If you could let me know the part number of the mosfet you used i would attempt to do the repair myself.
Thank you! The part number of my replacement transistor is IRLML6402. There is also a companion write-up here: drive.google.com/file/d/1Xyxnbd0tBw4rz8idYSstMwOpiL0UA4ya/view?usp=sharing let me know how this goes :-)
@@MrCircuitMatt My charger is only 2 years old and it didnt work from the time I received it. Same exact problem. So I ordered the part from Digi-key. Will let you know when it is done. Part is on back order. Thank you
With further inspection the green light does not come on at all and the red is very dim and does not charge at all - can I assume it is the same chip with a slightly different problem?
@@fixit1000 In this case you probably have to dive into a bit of debugging. It could be the FET but not necessarily. You could always pull the FET, test it and if it tests good the put it back in. That aside, I would first check if you have the correct supply voltage at the fuse, then check a number of other bias voltages, then check if the different transistors work as they should. This is relatively easy to do if you know how. I'm happy to help you in the process but youtube comments are somewhat tedious for this... could we perhaps move the discussion to email (I'm on QRZ) or some other means of communication?
Very well done!! I wish I had watched this earlier. I tried a couple of solutions and was about to use the M74HC125! I really appreciate your thorough treatment of the subject!
I hear you can turn this into a mobile repeater. I'm looking for something to use in my Jeep for when I go hiking with my baofeng and my Jeep buddies. I'm looking at an IC2730a but I'm looking for someone to guide me. I'm a newbie.
Hey there! It is true that this radio can be used as repeater, although input and output frequencies have to be on different bands. This is generally how mobile radios work as repeater, the term to describe this is "crossband repeater". You have to figure out whether this is what you are looking for and then find suitable radios (the IC2730a could be one). In case you are looking for somebody to guide you, drop me an email at hb9frv@uska.ch
