EEVblog
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- เผยแพร่เมื่อ 10 ก.พ. 2025
- Mailbag is back for 2017
Forum: www.eevblog.com...
SPOILERS:
Educational kits from
tronclub.com/
Electro-permanent magnet for UAV's and drones from NicaDrone
nicadrone.com/i...
Cisco VOIP phone teardown
1980's GE Cordeless phone teardown
Open source USB charger:
www.bloguetroni...
STM32 Development board:
www.tindie.com...
Max Chan is for hire:
en.maxchan.info/
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The 2nd EEVblog Channel: / eevblog2
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The Cisco IP phone does NOT use a standard power over ethernet pinout, they use their own pinout. Because clearly standard power over ethernet does not provide the optimal configuration for the best VoiP experience, but changing the pins around makes it perfect.
The copper lands can also be to balance the amount of copper on each side to help with the plating process - Eurocircuits online DRC checker will sometimes complain about designs with a big difference in density between sides.
Hi Dave:
I took the plung and decided to try Tron Club. Ill keep you updated as the kits come in. thanks for the channel
Whats the update?
"I won't take it apart.. or maybe I will." - Dave 2017
Those caps have series resistors (typically 100R) , not inductors - they're snubbers for use across contacts - the resistor limits surge current when the contact closes
glad you are back... was having withdrawal.
I think I might join the tron club. this would be perfect to show my daughters how circuits work. and also help me understand how electronics work. thank you for posting this. I've been watching your videos for a long time and never miss a mail bag. thank you Dave.
It looks quite cool.
I remember that GE cordless phone. They were very easy to eavesdrop using a scanner. You also hear other people's conversations on the same frequency. LOL 49.975 mhz.
Correct.. infact one of our national tv channel was broadcasting in nearby frequently and you guessed it, whenever our neighbor was making a call, we had some commercial breaks listing to her cheesy n 18+ phone calls
Did you notice the crappy layout on the Cisco IP phone? There are some DC/DC converters on the board, and they put the high-current loops on inner layers, rather than on the surface. That means their switching current run through the ground planes, probably making the whole board pretty noisy. Basic rule for beginner power supply designers: keep the two current loops tight and on the surface, and connect to the inner power/ground planes with vias only at the input, output, and common nodes. I haven't seen any videos on TH-cam about this, so it might be a good subject for one of yours, Dave.
Always nice to see another Mailbag, first one of the year too ;)
I hope you and your family enjoyed your vacation/get away Dave.
- A random Canadian
i think when there was that bit of residue magnetism with the electro-permanent magnet thing it was because you had magnetized the steel plate you were demonstrating it with.
good evening Dave!!! So happy your back hope holiday was great for you. Been looking forward to you coming back.
I really like the tronclub and the permanent magnet module! These might be the first items I get that I learned about on eevblog...advertisers take note!
Cisco is convoluted way of doing anything! I recall someone commenting semi-jokingly that back in the days, their security was provided by the fact that there were so many different builds made for router os.
Yay!! Mailbag. Welcome back, Dave.
I remember when we first got that Cisco system in where I used to work. the setup was a nightmare but it was reliable.
SWEET!!!!!!!!!!!!!! Dave's back!!!!!!!!!!!!!!!!!!!! "Let's have a squiz!" "We're in like Flynn!" I need all your catch phrases in my life, daily. Don't ever leave me again, Dave. While you were gone, I had to re-watch previous mailbags to get my fix.
You are awesome. I know very little about electronics but you are a very entertaining person and I watch you like I binge-watch series.. and well, the more I watch the more I know about electronics. Thank you!
Dave, the PWM input is what is used for controlling it, you would connect that to a spare R/C channel, R/C model systems use PWM for all servo and speed controller control inputs, typically it is a pulse that varies between about 1 and 2 milliseconds.
That's one way of disposing disposable wrist straps! 😂😂😂
A bit of info on the Cisco phone...
We are still using these exact phones for all desk communications. I work for a government department where calls made NEED to be secure. These are part of few fully closed systems left on the market. By fully closed, I mean we run the whole system, from call managers to end phones. The only thing that anyone else controls are the phone number allocations (we have a block of numbers we can allocate). The main feature of the phones we care about is the encryption. If someone makes an internal call from one phone to another, the call is encrypted end to end. Not even myself as an IT administrator can listen in, even though I have full control of the system.
The interface is a one-port PoE switch. You connect to a PoE switch and then connect your pc/laptop to the port for IP traffic. The other port is for console headsets and such. We still use them in the US.
Brilliant move by TronClub, that kit is going to pay for itself many times over. I think my 7 year old nephew is about ready for these, as long as we build them together.
Hey, if I tin the leads of all the components, and then bake the completed breadboard in the oven in a small tray, do you think its plastic will flow into the shape of a nice white featureless iDevice? Because, we're going to have a lot of breadboards by the end of this.
links from IF cans to crystals is very common in CB tranceivers and some ham radios too
Dave admits he is not savvy on RF, so we generally forgive him those bits of ignorance :)
The TronClub stuff is interesting. Looks like maybe the 2nd kit you got is actually the 1st kit, but from the Advanced stream, as both are "Kit #1" in the menu. [would explain the double bread-board]
I love the Tronclub idea, I have subscribed just to refresh what I have learned a long time ago.
Neon lamp on the handset antenna circuit? Shuffle your feet across the carpet on a cold, dry day holding the handset and then zap that whip antenna to a metal doorknob.
You'll see it light up, if only for a brief flash.
Very cool as always!
Regarding the electropermanent magnet, being a device for putting in drones and RC hobby gear, most definitively the PWM input is likely a standard PPM hobby receiver signal input. Quite convenient to operate the device from an assigned knob or switch in the RC transmitter.
1990s Nortel system phones have a very similar hookswitch with the spring wire and conductive plastic contact. Surprisingly, it seems to work well.
Dave you forget to open up the cisco handset, revealing the big metal piece for ergonomics and mention the great design behind the good feeling when you hold old cisco handset. In the newer models there are no metal weight... Cheers
be interesting to see how good the port isolation is on that antenna duplexer.
Those pushbutton-pulse dial phones were weird, but I took a lesson from them and built a relay-driven pulse dialer that connected to the joystick port of our Apple II+. With a database I built in Applesoft, I would use that to dial into bulletin-board systems nearby, so we could connect via acoustic coupler modem.
I believe the neon bulb in the antenna line was a low-tech static protection. It gave some bleed off in case there was a nearby lightning strike, or shocky carpets.
Brings back memories...good times, good times...
I think that we, the community of EEVBlog, should make a ultimate list of things Dave loves playing with! I'd start with:
- rod antennas
- nipples (nixie tube as well as VFD)
Please fill in the list
Tron Club looks amazing!
Long term reliability of the switch in that Cisco phone is directly tied to the amount of makeup worn by the user.
I'm sold on tronclub
It's quite expensive for a student, but you get a lot of amazing stuff plus good instructions and, the best part, you get steps to follow
But you don't learn anything from it.
Yes, i know
But for me it's more important to have a schedule than having someone explaining me what I'm doing
It would be great to have a teacher like Dave, i try to follow his videos, but most of the time i don't understand them because i just don't have the basics, i haven't build enough circuits to really understand them
@@macdonalds1972 ...soldering? Measuring/recognising elements you're about to solder? Getting closer to proper technique because of the occasional screw up?
You don't learn how to design a circuit just by putting it together, but plain "nothing"? Come on now...
love the videos keep up the good work ive learned so much watching your videos they definitely inspire me to go to school for ee n good to know theres fans in indiana thats were im from dont really seem theres alot of people here that love electronics design .
I don't mind at all if some companies want to show their products more than once. Maybe you could just put them on hold for some time and then show them like once a month at the end of mailbag video like you did this. Thanks for great video, Dave!
FINALLY BACK. happy new year
We had 3 out of 20 of those cisco phones fail because of the strange cradle mechanism.
The PM using his all the time broke two of the three in under a year. His solution was to use the speaker phone in the open plan office. Our solution was to bin his phone.
To be fair to Cisco none of our phones were brand new but they were allegedly reconditioned and can't with a warranty.
its certainly not long term reliability on the Cisco VOIP phone. We use those at work and we've had to replace several units because the hook switches would fail after just a few months. Especially in areas where the humidity would be a bit high. So many issues from those phones
Yeah I have alot of these phones at work. The hook switch is horrible for reliability. They're also an easy fix though. Just straighten that wire back out again and good for a bit.. I noticed there is a better design in later models.
Dave, the Tron Cub kits you were given, It look like you got t he first one of each range. Basic and Advanced.
EEVBlog ? Mailbag? 2017? Instant thumb up!
34:50 Dave keeps giving us sneak peaks at the new eevblog meter :-)
Dave you are getting close to EEVblog #1000!
I'll bet that mains cord attachment at 03:04 was not OEM, but was a replacement. I think the crimped splice seen at 03:23 confirms it, because who would want to pay assemblers to wrap a joint with tape instead of using a quick crimp? Also UL would have something to say about mains voltage being exposed when the tape lets go with age.
TronClub!! I'm very intrigued and think I'll subscribe. I had no idea that there was anything like that available. I can see TronClub being just wonderful for a child to be introduced to the field of electronics. These days, that could lead to all sorts of incredible things. This seems like something that would've been done before.
I noticed my mailbag videos are very popular too... seems people get excited about opening mystery mail!
Welcome back Dave!
I had a couple of the old Dick Smith beginner electronics kits, pretty sure I still have one kicking about in my credenza, I know I'm missing a few components though
I still own and use a cordless phone. In fact, it is right here on my desk weighing down papers that I've forgotten about :)
I'm so early the title is wrong. EEVblog #964 Mailbag* (instead of EEVblog964 Mailbag). Good video as usual.
You win a brass Razoo!
9+6+4 = 19 x 35.06 = *666* *ILLUMINATI CONFIRMED*
No u pece of sheet
Mathieu Riesling omg I think he knows how to spell and use a hashtag. How dare you. This is disgustingly rude to just totally correct him like this.
EEVblog i googled "brass razoo" and learned a new phrase! Thanks Dave!
I have a few Cisco 7961 in my lab. Their 'power budget' is 12.95W as it is a PoE device. The phone declares itself is a 'class 2' PoE device - which means it will never require more then 6.3W. I've never tested current draw on PoE to get actual numbers.
The sound it makes when magnetizing itself is similar to the sound of a marble bouncing on a hard surface; loud, infrequent pulses that get softer and closer together. Maybe you could use your scope and probe around a little?
having watched a few of your mailbags over the last couple of years i do wonder of a quick sneak peak at everything at the beginning of the vid would spoil the suprise or help keep people hooked
In Europe, analog cordless phones are forbidden now, since DECT is the standard for about 20 years now, and they have reassigned the frequency band (I think it was 480MHz) to some other use, so using an old analog cordless phone can really get you in trouble if your phone disturbs some other transmission.
However, the guy from Indiana (I forgot his name) who sent this in should wikipedia-google "pulse dialing", it was quite common in the 80s, before tone dialing was possible everywhere (they needed to upgrade the phone network hardware to digital dialers for that to work, while analog pulse dialing can work with mechanical dialers that lift up and turn for each number).
Dave, be careful with the 12V cig. lighter thingy from Red pitaya, they are known to spontanously combust into flames and giving 12V out the USB port.
9:38 the breadboard is probably so you dont have to tear apart other kits. as well as for new members
The phone cradle is done that way to stop the "ram" down of the handset on to the delicate switch and pcb.
*waits for more details on that meter!*
Where does one acquire one of those delightful "I only give negative feedback" shirts?
I posted something on the EEV forum about one of those lights I couldn't figure out. Mainly couldn't figure out why it was where I found it.
That cradle mechanism is oddly satisfying.
I'm signing up for tron club right now!
We had those Cisco phones (or very similar) at the last place I worked. The biggest problem with them was that they were too complicated fro their own good. If your job revolved around being on the phone I'm sure they were fine but if you just needed to make a call now and then they were a total waste of money. I seem to remember the call quality wasn't all that great either.
That Cisco on hook switch later got upgraded to an IR light chopper.
The interface box on the Cisco phone is a 3 port 10/100 switch with POE.
Something about the ,piracy‘ issue 1:50 : As you say, it was a great issue, that nearly anybody, who had a matching handset was able to enter your phoneline and make (long distance) calls over your line. So listening to calls was no problem at all that days. But also the anti-piracy-feature didn‘t work, if you knew how to work around it. haha... it was quite easy to crack those pairing mechanisms as long as it all was implemented in analog technique.
9:00 i see a TO-220 device, i love TO-220 devices! along with TO-3, TO-3P and TO-247
Dave, I could be wrong but I think the reason the cisco phone was designed that way was to minimize the clunkidy clickey noises when you hang up the phone in a quiet office, a apparent concern for many office products of the time, like ultra quiet keyboards, quiet mode bios settings for computer hard drives and fans and "hush" mode switch setting on the office vacuum cleaner.
So you had to whisper when you made a phone call?
Mac Donalds I never said it made sense but it was a thing
I've had to replace one of those RIVA capacitors in an old sewing machine. The smell was quite exceptional and there was a lot of water for some reason...
That kit is real cool!
I love Dave's videos and I know it's just for effect, but all I could think for the first few minutes was... "Now THAT'S a KNIFE!!!"
I absolutely love how Dave speaks ! I wish I could :(
Who else went LOL when encountered all these wrist Strips/bands came into sight, as soon as Dave opened that big box at 21:31...?! I even asked myself, what if there would be nothing inside besides all these strips...?
i picked up a couple of video phones from a yardsale i am hoping to turn them into a intercom system
Cisco zen....Could not help but notice the 10 pin Power Transformer used for the PoE 802.3AF compliant SMP power supply - I use the same transformer in one of my PoE compliant products!!!
I had to switch out all the rifa caps in my 70's sewinf machines only 1 had failed though was cracked and burnt. The other ones were just a precaustion since they were rated 220v and our line voltage is now 240-250 .
"Build in fault"
Sounds like brand new ripped jeans xD
I wish Dave would come out with his own "Get started will electronics kit" that would be so cool! I would buy the shit out of it.
The USB power bank is sold over here in the UK by Pound World for, you guessed it, £1!
They're pretty good.
You don't want to smoke these capacitors inside, trust me. Just had a similar one going off accidentally last week, and I almost couldn't get rid of the stench.
That Cisco phone looks identical to Yealink phones we have at work, even down to the sliding thingy next to the cradle switch. (Office models are have a much smaller display and this looks like a model that only the secretaries have.
I'm still using one of this this old radio-telephones in my own home!
It'd be interesting to see how much current/voltage those disposable wrist straps could take before they started to burn up (or would the carbon bit just get really hot?)
what a good way to start the morning before college ;)
Those Rifa capacitors were quite common to crack and still operate with it until moisture gets in.
the ones in my A77 R2R machine released their "beautiful" smoke when i serviced that machine and gave it a testrun to see if the main transport worked...after ten/fiveteen minutes...yea..some like artificial fog....but with an ugly, disgusting smell as well....that "Rifa" smell, for those who know....
What do you do with all the gear people send you after you open it and show to us?
Missed you Dave!
30:30 Send the powerbank to bigclivedotcom for testing :P
Shipping will cost more than the value of that thing.
I got the same powerbank for 3CAD at my local dollar store lol
What for? It's too weak to power the Red Potato.
Big Clive always takes the pink one. Its cos he is secure in his masculinity. :)
I had a scanner radio (went from .25Mhz to 1.3Ghz) and I could still listen in on a few calls made using this type of phone usually at around 30Mhz I think in the UK. This was back around 2007-8 I think everyone will have digital phones now.
That electronics kit reminds me a lot of the old Dick Smith Fun Way books I had when I was a kid.
Love your content! Thanks for being awesome!
I use the same type of Cisco phones at work...the hook switch might explain why one of them don't work right.
finally an Indiana shout-out on eevblog - never thought I'd see the day :p
Horror films scenes for electronics devices: Dave with a bowie knife saying "I'M BAAAAACK"
You're killin' us already with those vague multimeter teasers! Announcement anytime soon??? :)
ahhhh I needed my fix thanks dave👍
I'm still subscribed, and getting notifications as usual, didn't encountered any problem what so ever...
I think the electro-permanent magnet thingy, or probably a bigger version of it, could be useful for a new extreme sport: Roller-hitching!
Tge idea is, you tie your magnetised magnet onto the end of a long rope, and don a pair of roller skates. Standing on the pavement, you throw the magnet towards a car as it passes you, holding tightly onto the end of the rope, and try to attach to the car. When up to speed, simply demagnetise the magnet and reel it back in .....
I had an old cordless phone that I discovered some kind of debug feature that would let me listen to other phone conversations nearby. I think I had to hold the talk button while flipping a switch (mute or maybe ringer? I don't remember).