Remember how we said we’d give away an oscilloscope to a random person on hackaday.io if they have voted on projects for The Hackaday Prize? Last week we tried that and no one won. This week we tried it and no one won. Then, because we’re awesome, we picked another person at random on Hackaday.io. [Rafael] is the winner, with a very nice oscilloscope heading to his doorstep. We’re going to need some contact info, hacker no. 13951, and if anyone has any advice on sending expensive electronics to Brazil, I think we’re going to need it.
We’re doing this again next week, so head on over to hackaday.io and vote. Also, pay no attention to the people who say voting is too hard and complicated and ill planned: they are wrong, and if you suck up enough the Prime Overlord will command that t-shirts and stickers be sent out to you.
[Alan’s] friend came to him with a problem. He loved listening to his scanner, but hated the volume differences between stations. Some transmitters would be very low volume, others would nearly blow his speakers. To solve the problem, [Alan] built up a quick automatic leveling circuit (YouTube link) from parts he had around the lab.
[Alan’s] circuit isn’t new, he states right in the video that various audio limiting, compressing, and automatic gain control circuits have been passed around the internet for years. What he’s brought to the table is his usual flair for explaining the circuits’ operation, with plenty of examples using the oscilloscope. (For those that don’t know, when [Alan] isn’t building circuits for fun, he’s an RF applications engineer at Tektronix).
Alan’s circuit is essentially an attenuator. It takes speaker level audio in (exactly what you’d have in a desktop scanner) and outputs a limited signal at about 50mv peak to peak, which is enough to drive an auxiliary amplifier. The attenuator is made up of a resistor and a pair of 1N34A Germanium diodes. The more bias current applied to the diodes, the more they will attenuate the main audio signal. The diode bias current is created by a transistor-based peak detector circuit driven off the main audio signal.
But don’t just take our word for it, watch the video after the break.
Continue reading “Automatic Audio Leveling Circuit Makes Scanning More Fun”
The demoscene is alive and well, with new demos coming out on a multitude of platforms, including oscilloscopes. Beams of Light is a new demo released at @party in Boston by [TRSi]. Beams isn’t the usual .EXE file format for PC based demos. It’s distributed as a 4 channel wave file. The rear left and right channels are stereo audio. The front channels, however, are vector video to be displayed on an oscilloscope in XY mode.
Beams of Light isn’t the first demo to use an oscilloscope. Youscope and Oscillofun preceded it. Still, you can see [TRSi] pushed the envelope a bit with his creation. He used Processing and Audacity to create the vector video, and his own line tracing algorithm to reduce flyback lines.
[TRSi] included an updated copy of a python based oscilloscope emulator so you can play the demo even if you don’t have the necessary hardware. We wanted to run this the right way, so we powered up our trusty Tektronix 465 and hooked it up to a 1/8″ stereo plug.
Sure enough, the demo played, and it was glorious. We did see a few more retrace lines than the video shows. This could be due to our scope having a higher bandwidth than the 10MHz scope used in the YouTube video. XY demos are one of those rare cases where an analog scope works much better than a low-cost digital scope. Trying the demo on our Rigol ds1052e didn’t yield very good results to say the least. Sometimes good old phosphor just beats an analog to digital converter.
Continue reading “Beams of Light: An Oscilloscope Demo”
Sometimes we forget how many things we can do with a simple oscilloscope. In this video [Ben] uses one that Tektronix lent him to measure his DeLorean engine RPM. By checking the car main ~12V voltage one may notice that the voltage spikes occurring are directly related to the engine speed, as they are created by the inductive kicks from the ignition coils. Obviously the multiplication you have to do to get the RPMs from the number of spikes per second depends on your engine configuration (flat 4, v6…).
The method that [Ben] used was to search for high amplitude spikes on the (AC coupled) car 12V Fast Fourier Transform (FFT) to get a reliable measurement given the many electrical noise sources present in his car. At the end of his video, he however mentioned that it could still be possible to get a good measurement with a simple voltage comparator and a high enough voltage reference.
Continue reading “Measuring Car Engine RPM via the Cigarette Lighter”
Are you interested in building a 20kHz 2-channel oscilloscope and a 2-channel signal generator for only $20 with minimal effort? Be sure to check out [Jan_Henrik’s] Instructable that goes over how to build this awesome tool from a cheap USB audio card.
We have featured tons and tons of DIY oscilloscopes in the past, but this effort resulted in something very well put together while remaining very simple to understand and easy to build. You don’t even need to modify the USB audio card at all. One of the coolest parts of this build is that you can unplug your probe assembly from your USB audio card, and bring it wherever your hacking takes you. After the build, all you need is [Christian Zeitnitz’s] Soundcard Oscilloscope program and you are good to go. One of the major downsides that is often overlooked when using an audio based oscilloscope, is that it is “AC coupled”. This means you cannot measure low-frequencies (including DC signals) using a sound card. Be sure to heed [Jan_Henrik’s] advice and do not use your built in audio card as an oscilloscope. With no protection circuitry, it is a sure fire way to fry your computer.
What analog projects have you built around an audio interface? We have seen such an interface used for many different applications, including a few fun medical related hacks (be sure to keep safety your first priority). Write in and let us know!
As most of our readers know, [Mike] was visiting Bay Area Maker Faire last weekend with a big Jolly Wrencher on his back. During his tour he encountered the neat oscilloscope shown in the video above, made by the Belgian company Velleman. Even though it only has a 10MS/s sampling rate and a 10MHz bandwidth, our guess is that it may still be useful for some hobbyists out there as it can communicate with any PC/smartphone/tablet using its Wifi interface.
Inside the black box is a 3.7V 1800mAh Li-ion battery with a USB port to recharge it or update the oscilloscope’s firmware. As seen in the video, the tablet’s touchscreens may enable more natural interaction with the user interface. The protocol used to export the acquired samples is open, which may allow users to create their own analysis program. The oscilloscope uses an 8 bit analog to digital converter and a 4K samples buffer.
Now that [Bunnie]’s open hardware laptop – the Novena – is wrapping up its crowdfunding campaign, it only makes sense that development around the Novena project would move over to the more interesting aspects of a completely hackable laptop. The Novena has a huge FPGA on board, with 2 Gbit of very fast memory hanging off it. Also, every single signal pin of the FPGA is broken out on high-speed connectors, making for some very, very interesting possible add-on boards. [Bunnie] has always wanted a portable, high-end oscilloscope to carry with him, and with the new oscope module, he has something that blows out of the water every scope priced below a thousand dollars.
The oscilloscope module [Bunnie] is working on has either two 8-bit channels at 1 GSPS or one 8-bit channel at 2 GSPS with an analog bandwidth of up to 900MHz. The module also has 10 digital channels, so if you need a logic analyzer, there you go.
Being a fairly high-end scope, the hardest part of engineering this scope is the probes. The probes for fast, high-end scopes cost hundreds of dollars by themselves, so [Bunnie] looked for a clean-sheet redesign of the lowly oscope probe. To connect the probe to the module, [Bunnie] realized a SATA cable would be a great solution; they’re high bandwidth, support signals in the GHz range, and are rated for thousands of insertions. These active probes can be combined with a number of front ends for application specific probes – digital probes, ones for power signature analysis, and ones for capturing signals across small loops of wire.
The module itself isn’t quite ready for production yet, but by the time the Novena crowdfunding campaign starts shipping, [Bunnie] will probably be working on the next add-on module for his crazy awesome laptop.