brainwagon

I was in the mood to melt some solder, but didn’t really have a lot of time and/or brainpower last night, so I turned to my box of little electronics kits that seems to have been growing over the last few years. I located a small plastic bag which contained tanjent’s “bliplace”, a tiny kit […]

Over on the #savagecircuits IRC channel on irc.afternet.org, Atdiy was trying to decipher the mysteries of a mainstay of analog circuit design: the RC filter such as the one pictured on the right (diagram cribbed from Wikipedia) It dawned on me that (newbie as I am) I didn’t really have a clear understanding of them […]

I was pondering my laser transmitter the other day, and began to think of how I might transmit digital information from the Arduino to the remote receiver. Since I am old, I remember the old days where programs used to be stored on an obsolete audio storage medium called cassette tape. Indeed, the first storage […]

The other day, I showed how the Arduino could be used to generate PWM audio and send it over a very short distance using an LED. In my ever increasing pile of parts, I had some small 5mw red laser diode modules. These modules are supposed to be driven by direct connection to three 1.5 […]

I’m still interested in doing light based communication, but I haven’t made a lot of progress. I did build an LTSpice model of the circuit I used yesterday, but other than verifying that it probably would work as built (which it did) I didn’t feel like I had enough brain cells working to optimize the […]

Okay, so last night, after just testing one of the laser modules I had, I decided to try to make a transmitter to send audio over laser light to my “solar cell + Radio Shack amplified speaker” receiver that I was experimenting with earlier. I suppose I could have used my linear current LED modulator, […]

A while ago, I got some laser diodes from from dealextreme.com. They were dirt cheap, but I haven’t had any chance to hook them up. I didn’t have a datasheet for them either, so wasn’t sure exactly what I should do to current limit them. So, I hooked it in series with a 150 ohm […]

I was digging around trying to find some software to help me design a magnetic loop antenna for use on VLF frequencies. I stumbled across this page, which provided a lot of interesting insights, as well as a Spice model to help you understand how they work. Magnetic Loop Antenna Theory The article clarified something […]

Most of the websites that I link to are related to specific topics or projects. But every once in a while, you find one that has a bunch of good stuff that matches some of your esoteric interests, and you wonder how one person could do it all. Inspired by Jeri Ellsworth’s latest video showing […]

Back on June 7, there was a spectacular coronal mass ejection on the sun: Yes, I did mention this event and gave some links to VLF receivers at the time, but I’ve been thinking about this some more. As an astronomy/telescope buff, I have built simple telescopes for looking at the sun, but I haven’t […]

I was away all weekend, so I didn’t get a chance to check out my LEDs that I got from Deal Extreme last week. Tonight, I just soldered a couple of clip leads and tried it out when hooked to the linear current modulator that I built (and blogged about) before. The transmitter in this […]

KB6NU drew my attention to this article on using operational amplifiers in audio design. It’s apparently drawn from material in Douglas Self’s book Small Signal Audio Design. As someone whose really just become involved in the ins and outs of analog electronics, I find his pragmatic approach and explanations to be really helpful. Check it […]

Radio Shack recently posted this (as yet, not incredibly popular) video asking for feedback on what they could do to support the DIY/Maker community: I’ve thought about it off and on for the last couple of days, and read some other blog posts, and I thought I’d give my take on it. I mostly don’t […]

Fellow hacker Mike Cowlishaw tweeted me a reminder that he had worked on a design for a spelunker’s headlamp that used Luxeon LEDs, and had excellent high performance. I remember that I listened to a talk about this design, but at the time, I wasn’t saavy enough in electronics to grasp the details, and it […]

I’ve been pretty happy with the performance of my linear current based LED transmitter, but that was just sitting on the bench, driving a 20ma device. As I played with the circuit, I began to realize that if I scaled the circuit up to a 1W LED, its deficiencies in terms of efficiency would become […]