Collaborate Disseminate
If you’re designing a universal port, you will be expected to provide power. This was a lesson learned in the times of LPT and COM ports, where factory-made peripherals and …read more Continue reading USB And The Myth Of 500 Milliamps
[mircemk] built a slick-looking LED tester with a couple handy functions built in. Not only can one select a target current to put through an LED, but by providing a …read more Continue reading LED Tester Also Calculates Resistor For Target Voltage
[Mark Rehorst] tells us about a tragic incident involving an untimely demise of $200 worth of motor driving hardware, and shares a simple circuit so that we can prevent such …read more Continue reading Protect Your Drivers When The Motor Stalls
Running a brushed motor in muddy or dusty environments takes a toll on controllers, with both heavy back EMF and high stall currents. This explains one of the challenge in Europe’s Hacky Racer series, which is decidedly more off-road than America’s Power Racing Series.
In pushing these little electric vehicles …read more
Continue reading Battle Tested Current Limiter for Cheap DC Motor Controllers
Current limited power supplies are a ubiquitous feature of the bench, and have no doubt helped prevent many calamities and much magic smoke being released from pieces of electronics. But for all their usefulness they are a crude tool that has a current resolution in the range of amps rather than single digit milliamps or microamps.
To address this issue, [Yann Guidon] has produced a precision current source, a device designed to reliably inject tiny currents. And in a refreshing twist, it has an extremely simple circuit in the form of a couple of PNP transistors. It has a range …read more
In the real world, components don’t work like we imagine they do. Wires have resistance, resistors have inductance, and capacitors have resistance. However, some designers like to take advantage of those imperfections, something our old friend [Ken Shirriff] noted when he was restoring the CRT of a Xerox Alto.
[Ken] tried to connect a Xerox monitor to the Alto and — since it was almost as old as the Alto — he wasn’t surprised that it didn’t work. What did surprise him, though, is that when he turned the monitor off, a perfect picture appeared for just a split second …read more
Continue reading Xerox Alto CRTs Needed a Tiny Lightbulb to Function
Does it ever just kill you that someone in a factory somewhere got to have all the fun of assembling your bench tools? There are a lot of questionable circuit boards floating around the Internet, and they can replicate practically any section of a circuit. When it comes to putting a prototype these days you can pretty much just buy each block of your system’s overview flowchart and string them together. [GreattScott!] combines a few of these into a relatively useful variable power supply with current limiting.
Admittedly, this is more of academic exercise if your only metric for success …read more
Continue reading Build Your Own Import Variable Lab Bench Power Supply