Do you need an idea for a fun do it yourself gift for a friend or significant other? Look no further, [conductance] has you covered. He put together an awesome electronic puzzle box using all analog electronics. The puzzle case is shaped like an over sized die and is made out of wood. It also requires a small jumper cable and an external magnet to complete the puzzle.
This is a six-sided die, where each side has something different to offer. The “five” side of the die shows the progress you’ve made in completing the puzzle. Each of the five dots contains a green LED that will light up when the corresponding puzzle has been successfully completed.
The “one” side is completed by placing the included magnet over the dot. The magnet activates a reed switch which lights up the first LED. The “two” side contains a tilt switch. In order to solve this piece of the puzzle you must ensure the two side is facing up, as if you rolled a two. The “three” side contains three key switches. Each switch must be turned to a particular orientation. Once all three keys are configured properly, a third LED lights up.
The “four” side contains four sockets that fit the included jumper cable. This puzzle is solved by jumping the two correct sockets together. Finally, the number “six” side just has six momentary push buttons. All six buttons must be pressed simultaneously in order to light up the final LED. The tricky part is pressing all six buttons while simultaneously “rolling” a two in order to ensure the tilt switch is also activated.
Once all five LED’s are lit up, a relay is triggered which then activates a solenoid. The solenoid unlocks the door and reveals the prize. It’s always great to see electronics circuits like this that use all discrete components. This could have been accomplished any number of ways, but there’s something satisfying about a simple circuit that’s just right for the job. Be sure to check out [conductance’s] schematic if you want to see how this puzzle works.
Bob Widlar (1937-1991) is without a doubt one of the most famous hardware engineers of all time. In fact, it would not be an exaggeration to say that he is the person who single-handedly started the whole Analog IC Industry. Sure, it’s Robert Noyce and Jack Kilby who invented the concept of Integrated Circuits, but it’s Widlar’s genius and pragmatism that brought it to life. Though he was not first to realize the limitations of planar process and designing ICs like discrete circuits, he was the first one to provide an actual solution – µA702, the first linear IC Operational Amplifier. Combining his engineering genius, understanding of economic aspects of circuit design and awareness of medium and process limitations, he and Dave Talbert ruled the world of Analog ICs throughout the 60s and 70s. For a significant period of time, they were responsible more than 80 percent of all linear circuits made and sold in the entire world.
Continue reading “Heroes of Hardware Revolution: Bob Widlar”
Back in the days of analog TV, vectorscopes were used to view video signals. [Aaron] has taken an old Tek 520A NTSC vectorscope and converted it into his newest oscilloclock.
The scope was originally designed to look at the signal provided by composite video. It draws vectors on a polar plot. By using test patterns such as color bars, you can ensure equipment is creating the correct color output. These scopes were so commonly used that many digital systems still provide a simulated vectorscope for color analysis. Vectorscopes were designed to be left on constantly, which is a good quality for a clock.
[Aaron] has a history of converting oscilloscopes into clocks, which we have featured in the past. This build is similar, using his custom control hardware to drive the display. Since analog vectorscopes are pretty much obsolete, you can find them on eBay at low prices, so these oscilloclocks could be relatively cheap to build.
In the write up, you get a teardown of the Tek 520A, showing the modifications made to build the clock. After the break, check out a video of the Tek 520A Oscilloclock.
Continue reading “A Video Vectorscope Oscilloclock”
[Ryan] wanted a spectrum analyzer for his audio equipment. Rather than grab a micro, he did it the analog way. [Ryan] designed a 10 band audio spectrum analyzer. This means that he needs 10 band-pass filters. As the name implies, a band-pass filter will only allow signals with frequency of a selected band to pass. Signals with frequency above or below the filter’s passband will be attenuated. The band-pass itself is constructed from a high pass and a low pass filter. [Ryan] used simple resistor capacitor (RC) filters to implement his design.
All those discrete components would quickly attenuate [Ryan’s] input signal, so each stage uses two op-amps. The first stage is a buffer for each band. The second op-amp, located after the band-pass filters, is configured as a non-inverting amplifier. These amplifiers boost the individual band signals before they leave the board. [Ryan] even added an “energy filler” mode. In normal mode, the analyzer’s output will exactly follow the input signal. In “energy filler” (AKA peak detect) mode, the output will display the signal peaks, with a slow decay down to the input signal. The energy filler mode is created by using an n-channel FET to store charge in an electrolytic capacitor.
Have we mentioned that for 10 bands, all this circuitry had to be built 10 times? Not to mention input buffering circuitry. With all this done, [Ryan] still has to build the output portion of the analyzer: 160 blue LEDs and their associated drive circuitry. Going “all analog” may seem crazy in this day and age of high-speed micro controllers and FFTs, but the simple fact is that these circuits work, and work well. The only thing to fear is perf board solder shorts. We think debugging those is half the fun.
[Spider!]’s contribution to the pantheon of paintball markers is the SMAC: a unique revision to one of Airgun Design’s ever-popular Automags. We needed our tipster, [Russell] to provide some context on the Automag’s evolution, because the brand has served as a popular hacking platform for nearly 20 years. The most frequent is a “Pneumag” modification, which converts the original, fully-mechanical trigger pull into a version where the trigger actuates a pneumatic cylinder to fire the gun.
According to [Russell], the Pneumag’s trigger must completely release between each shot to properly recharge the firing chamber. Without a full release, the gun can load extra balls into the barrel and lead to gloppy consequences. Electronic controls solve this problem, but [Spider!] favored an analog solution that captured a “less is more” mentality over a pre-fab microcontroller board. He built the circuit around a 556 timer used as a delayed re-trigger, but with a few modifications.
Swing by [Spider!]’s forum post for additional details, a cluster of pictures and a bill of materials. Microcontroller alternatives? We’ve got you covered.
This analog drum machine project synthesizes a kick and snare drum that are clocked to a beat. It pulls together a few analog circuits to do the timing and synthesis.
The beat timing is a product of a hysteretic oscillator used to create a ‘shark wave,’ which is a friendly term for the output of a relaxation oscillator. This waveform can be compared to a set point using a comparator to create a slow square wave that clocks the drum beat.
The kick drum is synthesized using another hysteretic oscillator, but at a higher frequency, creating a triangle-like waveform at 265 Hz that provides a bass sound. The snare, however, uses white noise provided by a BJT’s P-N junction, which is reverse biased and then amplified. You can spot this transistor because its collector is not connected.
The resulting snare and kick drum wave forms are gated by two transistors into the output. Controlling these gates allows the user to create a drum beat. After the break, check out a video walk-through and a demo of the build.
Continue reading “Analog Drum Machine”
[Kerry] set out to build a digitally controlled dual supply for his bench. He’s already built a supply based on the LM338 linear regulator, but the goal this time was to build it without a linear regulator IC, and add digital control over both the current and voltage.
In part one of the build, [Kerry] explains the analog design of the device. He had an extra heatsink kicking around, which can dissipate enough heat from this linear supply to let it run at 10 A. A NE5532 opamp is used to track a reference voltage, which can be provided by a DAC. The current is measured by a LT6105 shunt sense amplifier, then compared to a reference provided by another DAC.
Part two focuses on the digital components. To interface with the analog circuitry, two MCP4821 DACs are used. These are controlled over SPI by an ATmega328P.
Fortunately, [Kerry] also has his own DC load project to test the supply with.