Short video showing how to test relays with a modified oscilloscope. Identify contact bounce, burned contacts, contact resistance, sticking relays, and faulty internal structure.
That would be really useful for finding intermittent failures in relays. Would love to make a circuit that could do this with the xy mode on a normal scope.
Curve tracers are fantastic, can build a very simple one with an LM324, centre tapped transformer and a few passives. Very nice demonstration of using the curver tracer
Well done Paul. I know this video is 2yrs old but I only recently discovered your channel and I am trying to watch all your content. I never considered the "lag" in switching times of a relay. Once I complete a few other projects in the "shack" I am going to build this tester. 73's Steve
Interesting technique that never occurred to me, thanks for showing it. What I have done for relay checking was to use a relay driver and trigger a scope off the rising or falling edge of the coil pulse*, and look at the voltage across the contacts, with a resistive load and a 12V or so supply on the contacts. Then I can read pull-in and dropout delays directly off the X axis, and see chatter and bounce or contact resistance from the trace shape. *Actually off a second output of the driver so that coil inductance doesn't affect the trigger.
WOW Nice piece of test gear. May I ask if it is possible you to send me the Schematics of the relay Tester Please. I have a bunch of salvaged relays both laching and non I wish to check out. Thank you in advance and keep up the good work.
...Reminds me of the job I had from1971-1979.....Burgmaster....Numerical Controlled Machine tools....the last of the dinosaurs before the CNC...control panels (2), 30" by 60"...each contained around 175-200 4PDT 24 volt relays....I don't recall the brand, but they were top quality stuff...
+Mr Carlson's Lab ..Yes, lots of relay drivers in the NC cabinet, mostly NPN sink to low...most relays had +24 DC on the coils...and the Turret location/indexing was in fact using magnetic reed switches for position output. The only Burgmaster stuff I see on any RU-vid is the tiny benchtop units...6 stations...all mechanical....the machines I worked on (as Elec-tech) were 3 axis...8 position turrets. tapered toolholders...20X40" X-Y axis...12-16" Z...all ball screw stuff... Machines were pretty well built...but Burgmaster folded in the early 1980's...they tried making some vertical tool-changers, but the biggest issue was the 'Union' wouldn't let them use any 'Japanese' control systems....seems about this time MAZAK was starting the true CNC....burg units used GE controls...XYZ was PWM driven, but spindle motors were crude SCR drives....many large PC boards filled with 7400 series TTL....5 volt, 60 amp power supply! Also the feed/rapid was slow, very slow compared to todays stuff...400 IPM rapid...40 IPM max feed... In the 70's...when I was there...Burgmaster was about as good as Cincinnati Milacron...also 8 position turret machines..
+Mr Carlson's Lab ...Well, actually I'm more of the ..."Jack of all trades, Master of none".....most work in the last 30 years...welder, maintenance mechanic/electrician, Auto A/C tech...and I actually designed/built/installed a vehicle bridge in 2003...big enough you can see it on Google Earth!! ....lots of 3-phase experience with X-formers and motors/switchgear...up to 5,000 HP (4160 VAC) steam turbine water feed pump in 35 meg-watt bio-mass plant....Turbine output was 13,500 VAC...! I really like your (and Applied Science) videos...a good deal of it is a little over my head, but I like the detailed explanations for everything...! I'm pretty much a high school grad (1964)...everything else I'm 'self-taught'...! Burgmaster was in Los Angeles...but I went to the annual 'Trade shows' with free tickets from employer during the 1970's......saw Cincinnati, and other stuff at Los Angeles Convention Center....also went to a couple Machine Tool shows in 1990's in San Jose, California area...very impressed with the first 3-d printing....UV laser and liquid resin...around 1995.
Hello. I'm a HAM radio YO3AOE - Nelu from Romania. Is it possible to send to me the schematics for this modification of the oscilloscope Eico 430? I have been looking for such a mod schematics, but so far not very much luck. Thank you. Nelu
Can I use a Tektronix 317 with an octopus? It keeps scowling at me from across the bench. The other day I heard a small voice "ain't no shelf queen"- I've since removed all sharp objects near the scope. Any advice would be greatly appreciated. Thanks!
The 317 would work great! If you would like to build that "octupus" on steroids, check out the curve tracer build on Patreon. The PCB plans and all are there..... And sized as well, so just print and build.
Mr Carlson's Lab Well, Ya Know... I think that's a great Idea Paul. I will do that. Dan here BTW, Full Wave is my secret squirrel electronicals handle ;) I also picked up a NC 300 with the 317 and it seems to work fine. But I don't have a decent antenna yet. I'm in an apartment, 3rd floor, hung a single strand wire out the window and heard voices again... Not from the 317, from the 300. Does that sound like a "healthy" Receiver to you? I'm new at this but I'm reading Radio Essentials and watching you and all the other usual suspects. I'm having a ball thanks to you! Looking forward to your next Vedolyzer vid. Hehe. Take care!
I wasn't clear how you hooked up the curve tracer to the relay. Is it just showing the X-axis voltage sweep connected through the NO relay contact? And I'm not sure what I'm seeing when the curve slopes counterclockwise on the tracer ...
Jason Olshefsky Hi Jason, simply put: A vertical line is contact closed. A horizontal line is contact open. Anything in between is resistance, IE: a 45 degree angle.
I am planning on using one :). At high switching speed, but within it's rating range. For example, if the manufacturer's data is 7 ms operating time and 3 ms release time, can it be used for 50 break and make operations in second? The load is resistive.
When you say 7ms, are you talking about the time difference between the voltage applied to the coil and the contact coming in? My little board will run at 50Hz no problems. Is this a reed relay, or an old electronic vibrator?
Mr Carlson's Lab No, not a reed relay, but 40.51 you can see specs of here: www.finder-relays.net/en/finder-relays-series-40.pdf The operating time is the time from the initial application of power to the coil until the closure of the contacts (excluding bounce time). The release time is from the removal of the power to the reclosure of the contacts. Such relays are not supposed to work continiously at such high switching frequncies, but judging by these times, theoretically they could for several seconds (than long pauses). Would be interesting to test.
Chevy cars some model the starter kept turning after you let go of the key sh my question do relay become slow some time before they let go of the position to stop turning the starter on a car
WOW Nice piece of test gear. May I ask if it is possible you to send me the Schematics of the relay Tester Please. I have a bunch of salvaged relays both latching and non I wish to check out. Thank you in advance and keep up the good work.
