One of the many functions a digital oscilloscope offers over its analog ancestors is a trigger button. Alongside the usual electronic means of triggering the instrument, you can reach over and press a button to “freeze-frame” the action and preserve the trace. Sometimes doing it repeatedly it can become a chore to reach for the ‘scope. That’s where [Kevin Santo Cappuccio]’s remote trigger button comes in.

The button itself is about as simple a hack as it gets. The ‘scope was carefully dissected and some fine wires laid from the contacts within the front panel to a connector on the case. From there a cable goes to a box with a momentary action button switch. Plug in the box, and you can trigger the ‘scope from a distance!

We have to admit to rather admiring this hack, as needing to trigger the ‘scope is a well-known problem here. It’s easy to stab the wrong button and lose what you are looking for, so we’re rather surprised we didn’t think of this one ourselves. But then again from another viewpoint, it involves dissecting an expensive instrument which is best left unmolested. Perhaps manufacturers should consider adding this functionality.

This may be the most straightforward oscilloscope hack we’ve shown you, but it’s certainly not the first.

I really don’t understand why oscilloscope manufacturers do not include such feature into their the high-priced probes. While megohmmeter insulation meters already have such feature: “TP165X probe” is an example.

$500 DLC consisting a $0.10 in wires, $1.00 push button switch, and a few other parts

Rohde & Schwarz have a configurable button on their active probes (available on single-ended ZS series and differential-ended ZD series) which can be used to perform a variety of functions such as run continuous, run single, auto set, auto zero, set offset to mean, and screenshot.

Why poke around in the scope’s circuitry?

Just make a button with a 3V coin cell and a pull-down resistor, but a BNC on it and connect that to the external trigger input. Set the scope to ‘auto trigger’ mode and bob’s your uncle.

A hack without having to mess around with the scope.

When people decide that cookies are a good thing.

Yeah no, cookies were a “good thing” before advertisers ruined OUR internet and web. The protocol was never meant for them in the first place.

Notice how the scope in question *doesn’t have* an external trigger input?

better question: what is this sBus interface? It appears not much reverse engineering has been done, but that’d be the place I would expect a trigger channel to go.

sBus is the 16ch logic analyzer input over an HDMI connector. I guess they could have used a bit on that port and set the scope to trigger on it instead of opening it up. But that wouldn’t have been as exciting.

Then you trigger on a spare channel.

With a 4ch scope that is still a viable option.

On that subject… why are ext trigger inputs disappearing? These used to be common on all scopes analog and digital since the 70’s

Considering how most scopes is “just an FPGA” then it wouldn’t be too hard for the manufacturer to include a trigger input. Protection circuitry adds a bit of cost, as well as the connector and labor to put on the retention nut. But it is honestly a very very useful feature. (and honestly, a switchable 10k ohm, 5 V pull up resistor built in would be a killer feature.)

And for scopes that don’t use an FPGA, these often use a dedicated chip that often does have a trigger input as an option. But these are for the larger fancier scopes that often has a trigger in. (except for a few that somehow don’t have a trigger in for some reason.)

Personally I like a trigger in. Regardless of how many channels the scope has on offer. Trigger out is likewise nice to have as well.

Bob is not my uncle. :-D

I prolly woulda went for a foot switch, hands free.

That’s not how auto trigger on my scope works. The project here still triggers on the actual signal, the pushbutton just enables triggering. Triggering by push button directly would only work for repetitive signals, enabling triggering allows starting the scope just before some event is about to occur.

The question on the beginning of this article is wrong! I thought many times about a triggerbutton und it is quite easy. Programm a small controller to send the command to the scope with RS232 or even to the network for modern scopes. But when I am working in complex situation all my finger are used! So we need a bigger MCU that will understand “Trigger baby!” Or a Mr Spock eyebrow movement detector?

That’s what foot pedals are for – or will you be kicking around a variac while probing ;)

I came here to see if foot pedals were mentioned. Thanks!

Maybe I’m unusual, but I like to trigger on a repeatable event, not something with the variability and latency of a human.

But sometimes you want to study only one trace of a repeating event, which you cant do if it triggers 10 times per second (for example)

That’s what single-shot is for. Hammering it repeatedly if that’s what it takes to get the ‘right’ event. Btdt.

If the event is repeatable then you only need to look at one instance of it, they will all look the same on your scope.

No. The trigger (eg ch1 rising after a gap of at least 100ms) being repeatable does not mean the events after it (maybe on other channels) are repeatable.

Having said that, another comment says it’s enabling the trigger, not acting -as- the trigger, be which is considerably more useful.

Yeah, my reading of the writeup is that this is a button in parallel with the single sample button, so you can repeatedly single-trigger. This could be annoying depending on the scope. Tek scopes seem to alternate single trigger with stop, so you toggle back and forth between the modes, while my LeCroy means single when you push single.

FWIW I’ve done something somewhat similar albeit requiring a LOT more hardware: almost all my work is done via SCPI/GPIB so I have a labview setup that every time I hit the space bar on the controlling computer, it sends a *TRG to the scope. It’s really handy but vastly more complicated.

My wife is working on a similar project, but using ethernet to send the command and foot pedals to trigger it.

The lazy man no reach button is a solid idea but I’d go with a foot pedal. Hands often holding probes & my scope is on an arm deep into my desk.

Trigger on a spare channel, external trigger port, Rs232 or even IP…

Not rushing out to crack open 8k worth of test gear when there are a ton of other solutions that would probably piss of Tek a lot less when I send it in for cal.

This reminds me of a similar problem. A few times my coworker has asked me “hey, can you pause the scope” because he was holding probes with both hands. We both wished for an alexa interface to control the trigger. Obviously it would be useful only for timing-insensitive cases, but in many cases that’s good enough.

Ask, and you shall receive:

There are commercially available scope probe holders that are similar to IC probe station holders: weighted base and some adjustability so you can clip the probe in and line it up and drop it into contact with the point you’re trying to touch. It’s nice because in theory you’re a lot less likely to scootch around and short to an adjacent pin while trying to reach over and hit single on the scope.

or Mechanical locking camera shutter release remote control and printing 3d adapter click clack

Scopes that understand SCPI can be triggered from a computer.

and armed in single shot mode, which is perhaps even more useful

Yeah, this could have been an ESP32 rigged to send a trigger command via SCPI. But I respect the direct approach.

Looks more like a case of someone who doesn’t know how to properly configure a single shot trigger. Bonus points if you change the settings to keep what came before the trigger in memory.

It’s a cool little hack, but potentially bad for the ‘scope. The lines to that switch weren’t designed for external connection and likely don’t have any protection on them.

I would like to have seen a little circuit tracing done first, with the aim of adding protection diodes and resistors as appropriate. Static discharges, or accidentally plugging the wrong thing into that audio jack, might make the internal electronics of that ‘scope very unhappy – perhaps permanently…

Good point! One could use an optocoppler with power stolen from somewhere inside the scope.

I did not check, but maybe this scope as some trigger-connectivity at the back?

The T10000 debug stations for the PlayStation 2 came with a foot pedal because your hands would be full with a controller generally. Like everyone else that said here – I was sold on the idea after that. It would be an easy upgrade.

I don’t think anything is stopping anyone from operating that button with a foot. Cool project.

Maybe I was dreaming, but pretty sure I used some scope that had a button on the probes that could be configured to be single shot arm, stop triggering, force trigger, identify probe, etc. Brief searching revealed nothing, but it must have been one of HP/Keysight (or whoever they are today), Tektronix, LeCroy or Yokagawa as they are the only ones I’ve used.

All these comments have triggered me! So I will now have to think of a calming slowly rotating Lissajous figure to calm down.

An Idea I’ve had for a long time is to make a dedicated USB “Keyboard” with a bunch of rotary encoders and buttons that looks like a normal oscilloscope interface. With such a box you can greatly improve the user interface of a PC based scope.

I’m actually quite surprised that for example Picoscope, which makes lots of USB based scopes, does not have such a box .

Hewlett Packard used to build lots of test equipment with Option 001, which was a delete of the whole front panel, for test equipment that was used purely in an automated test environment. As a result, you can sometimes buy Opt001 equipment for really cheap because nobody else wants it. I’ve seen DIY SCPI/GPIB panels built to talk to these, although most people use the USB scope route of making a virtual front panel.

Hi gang. I know virtually nothing about a scope, but being a commercial electrician, switches are my life. As an outsider looking in I would have to suggest a simple air switch. Nothing but a button that’s connected to an air bladder and any length of tubing you need with another diaphragm at the other end to actuate an actual button. Every home Depot in the world carries them in their garbage disposal section. Just simply remove the included electrical switch and stick the pneumatic workings right over top of the switch on your scope add whatever length of tubing you’d like you can use it on the floor, on the table, squeeze your thighs together to trigger it, whatever you’d like. And of course without purchasing a commercially made product the very simple concept to create on your own. I really enjoy reading your site guys hope this may be helped somebody somewhere out there.

Figured this way you don’t risk injury to high$ equipment, and since your still using built in button, there’s no doubts as to how it will function.

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