#934

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IMSAI Guy

2 жыл бұрын

Episode 934
Let's take a look at diode switching. I'll use a generic 1N4148 for this demo
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Пікірлер: 41

@markwhi1 2 жыл бұрын

Thank you! I've never understood how you could use a diode as a switch, this is very helpful.

@andye2005 2 жыл бұрын

Use the 1N4007 diode, they have a intrinsic layer (sort of) to give the higher voltage rating. This makes them work more like a real pin diode, and they can handle a bit of power rather than just small signals. Andy

@w2aew 2 жыл бұрын

I have a few videos on using diodes as switches, including PIN diodes too: Basic of using Diodes as switches: kzfaq.info/get/bejne/j6h-fNSQyZuao3U.html Basics of PIN Diodes and RF switching: kzfaq.info/get/bejne/jtaJpqZ-xL3KZWQ.html

@pjmccracken 8 ай бұрын

Thanks for this clear explanation, I was trying to understand how this worked on the sbitx v2 for band filter switching, in less than 4 minutes you have explained it in a way that it now makes perfect sense. Thank you!

@itsevilbert 2 жыл бұрын

Thank you. I love it when I learn something totally new (to me), about what I thought I knew.

@edieharo4186 2 жыл бұрын

For sure, I'm learning a lot here, Thanks again

@jainmanish123 2 жыл бұрын

Thanks for a very nice little switch circuit tutorial

@tomsmith3045 Жыл бұрын

great short demo and explanation!

@SteveWrightNZ 8 ай бұрын

You can also use the diode to short a quarter wave transmission line, to make an isolated point 1/4y back alone the line from the diode.

@SerialNumber-jm1sg 4 ай бұрын

*40. Good day! It's Nice to have it so clearly explained! Thanks a lot! May I ask about choosing such diodes for example 50W RF out put power?

@GospelOfTimothy 5 ай бұрын

Hello, I have a small power supply for a clock/timer that went out and I think it's the zener switching diodes. I'm supposed to get 10 volts output between the positive and negative and I'm not getting no output and the voltmeter is showing a short between the positive and negative on that 10 volt rail. I seen some replacement diodes on eBay, but I'm not sure the correct voltage or amps by looking at the diodes in my circuit. I was hoping tge 100 volt 0.3 amp would work. Those are the ones that look like the ones I need on eBay. It seems like a very simple circuit power supply for a clock. there may be something else that's bad on it. but these inner diodes are letting electricity through that causes the short between the positive and negative.

@RK-kn1ud 2 жыл бұрын

Very cool! Thanks.

@SahanaC_Sana_ Жыл бұрын

Immensely grateful!!!!🙏🙏🙏Thank you!!!!!!!

@miguelmiguel7314 2 жыл бұрын

two weeks ago I were making measurements with nano of that diode, dinamic resistance and internal capacitance. Internal capacitance is surprisingly lower than the max permissible in data sheet.

@corbacktoztoz703 Жыл бұрын

Thanks a lot

@paulpkae 2 жыл бұрын

Brilliant explanation. What size capacitors would you recommend for audio ? Also, if your output is onward connecting to a high or low impedance input would the 1K to ground cause some signal attenuation?

@jbrown468 2 жыл бұрын

Great video, @IMSAI Guy. Thanks! One question: when would one need an inductor on the bias to prevent RF from running to the power supply?

@IMSAIGuy 2 жыл бұрын

yes, most designs do

@jbrown468 2 жыл бұрын

@@IMSAIGuy can you do a video on that someday? Thanks for the response! 👍

@krish2nasa 2 жыл бұрын

Nice, does that diode create any intrinsic noise even If it is minute? Thank you very much?

@JKKLSHH 4 ай бұрын

do you know MMP1440-GM2 pin diode in ads spice modle? thanks

@jeanpottecher2863 2 жыл бұрын

Thank you for the video ! Does anyone have a reference of a PIN diode to look at it's datasheet ?

@IMSAIGuy 2 жыл бұрын

google "pin diode datasheet"

@supurity2676 2 жыл бұрын

Great video, thank you! One question: if I want to measure the S11 and S21 parameter of the PIN switch circuit as shown in your video. Should I just directly connect the outer conductor of the SMA to the DC ground (the negative pole of the 5V power supply), and the inner conductor to the input/output?

@IMSAIGuy 2 жыл бұрын

all grounds were common in my setup

@supurity2676 2 жыл бұрын

@@IMSAIGuy That's helpful. Thank u for the response 😊

@K1ZEK 2 жыл бұрын

Nice job! 73 Leo

@eddy2561 2 жыл бұрын

Wax on, Wax off

@technishn 2 жыл бұрын

I heard that normal diodes shouldn't be used for diode switches for RF, as they create Intermodulation (IMD).. Is that the case?

@IMSAIGuy 2 жыл бұрын

they probably add some non-linearity. the PIN will have a linear region if you keep the signal amplitude small

@pyrokinetikrlz 2 жыл бұрын

waaaaaait a minute! How come that the negative semicycles of the AC signal are not getting thru the diode? You should get a half-rectified sine, right? How large is the AC signal amplitude and the threshold voltage of the diode?

@jainmanish123 2 жыл бұрын

Probably a 100mV signal and vf is about 0.7V so its not conducting the negative cycles and just leaking a bit

@pyrokinetikrlz 2 жыл бұрын

@@jainmanish123 that's what I thought, but i think it should have been said in the video :(

@pyrokinetikrlz 2 жыл бұрын

@Bill Carson wow! Even 1V signal? That's interesting considering that threshold voltage of diode is about 0.7v

@nickcaruso 2 жыл бұрын

iirc the way it works is, the forward bias saturates the junction and the diode is slow to recover, so the ac passes. the “I” part of the PIN diode adds capacitance and makes the diode even slower to come out of saturation. if i am remembering this right.

@w2aew 2 жыл бұрын

There is some charge stored in the junction when forward biased. When the polarity across the diode changes, the diode WILL conduct in the reverse direction until this stored charge is removed. If the negative half cycle doesn't last long enough (or isn't large enough) to completely remove this stored charge, then it never goes into blocking (and just looks like a low impedance path to the signal). This stored charge is what is also what is responsible for the reverse recovery time in diodes.