Tuesday, March 31, 2009

Sneaky Design


I received the prize today (for electronic design) that I previously blogged about: a sophisticated device which measures inductance, capacitance, and resistance (an LCR meter). I thought I would throw the ultimate challenge at it -- a small halogen bulb (see photo). Such bulbs have both inductance AND resistance, and both are so low that either could represent an impossible challenge. My new meter thought for several seconds, then reported: “Low Resistance and Inductance: Resistance 0.4Ω, Inductance 0.2μH.” OBSERVATION: VERY clever! Well done to the designers, Peak Electronic Design Ltd.

Monday, March 30, 2009

BB Metal Detector


One of my better-known electronics feats was the design of the world’s simplest self-contained metal detector (see diagram). This is based on the Beat Balance (BB) principle -- also one of my inventions. The design shown here, despite using just five components (not counting on-off switch), offers sensitivity way beyond that of Beat Frequency Operation (BFO). If well adjusted, it will pick up an old English penny at 150mm (6”). Briefly, BB uses two search oscillators, and each search coil modifies the frequency of the ad­ja­cent oscillator through inductive coup­ling. This sets BB apart from BFO, which uses a single search oscillator and a reference oscillator. It also sets it apart from Induction Balance (IB) which uses one "transmit" oscillator and a "receive" circuit. OBSERVATION: This design is bas­ed on two extremely sim­ple in­ver­­ter oscil­lators (also my original design). Their outputs are then mixed, creating an au­dible beat frequency in crystal earpiece X1 (note that this is not the same as a high impedance ear­piece). The circuit is tuned with VC1, an ordinary AM tuner. For details on the construction of search coils, see http://thomasscarborough.blogspot.com/2008/05/bfo-metal-detector-2.html. Attach the coils to the circuit via balanced (figure-8) mic­ro­phone cable, with the cable's screens going to the coils’ Fara­day shields and -12V (negative). The coils may be bound to a rigid plate with cable ties, and should overlap each other by up to one-third (experiment for best sensitivity -- this requires meticulous movement of the coils before binding). It makes some 20% dif­fer­ence to the metal detector’s sensi­tivity “which way up” coil L2 is. Flip L2 to find the side which offers best per­form­ance. An improvement could be made to the stability and sensitivity of the circuit by using a regulated power supply. You may enlarge the diagram by clicking on it. Once again ... happy hunt­ing!
.
NOTE: You may re-publish this design, on condition that you acknowledge the designer (Thomas Scarborough) and this blog (http://thomasscarborough.blogspot.com).

Emergent Launch: Cons


Following on from the "pros" of Cape Town’s InVia Emergent Church launch, here is what I experienced as two “cons”: 1. The Church claimed to be “inclusive”, “crossing borders”, “releasing the Church across culture ... across all domains”. It was not about “a privileged inner circle”, and so on. Yet attendance appeared to be 100% White Afrikaans-speaking, and, by far, made up of affluent young adults (see the photos -- and InVia’s website at http://www.invia.org.za/). For an impression of society as I know it, see this blog. And 2. InVia’s self-description was one of “inclusiveness". It rejected “exclusion” and “in/out” dualisms (including Muslim, Hindu, Christian, Jew). Yet at the same time, InVia rejected other Churches’ “obsessions”, people’s “laughable” outlooks on life, denominational conceit, and so on, with much of the censure being too vague to make out precisely who was intended, e.g. “religion”, "pseudo-truth", “exclusivity”. This was a strong accent of the launch. OBSERVATION: Personally, I felt confronted with too many contradictions here. This "real" Church seemed to be too "unreal" for me -- yet nobody seemed to notice.

Emergent Launch: Pros

Following on from yesterday’s post re Cape Town’s InVia Emergent Church launch: the venue was first class, the Church very well equipped, the music ministry superb, the presentation excellent throughout. I received a personal, and personable, welcome from the minister himself. Coffee was served in a pleasant courtyard. There was the sense of emotional transparency, a dismissive attitude to “accustomed” religion where “words run ahead [of praxis]”, and a strong emphasis on “the [a] heart of worship” (I am translating from Afrikaans). Everyone received the Church’s new Manifesto. The immediate impression was one of a dynamic style -- while not Pentecostal. And the emphasis was on an "invitational" gospel. OBSERVATION: At first I wondered what was “emergent” about this. More in the following post ...

Sunday, March 29, 2009

Emergent Launch


Tonight I attended the launch of InVia, a new Emergent Church in Cape Town (see photo) -- or more accurately, a replanted Emergent Church. The service was held at the exclusive Reddam House, about 2km/1.3mi from our Church. For a launch, it was fantastic. There was a rapt audience of nearly 100, and the service and everything surrounding it was very well prepared. I’ll bring a more detailed report in two coming posts, in which I describe both pros and cons (according to me).

Tuesday, March 17, 2009

Another Prize

So much for asking an Australian editor to withdraw one of my designs (see yesterday’s post). Not only has the design been published, it has won a prize. I despair. OBSERVATION: Thanks to Silicon Chip Publications Pty. Ltd. and Peak Electronic Design Ltd. for the prize -- a very nice piece of test equipment. (See also http://thomasscarborough.blogspot.com/2008/11/prize-for-ingenuity.html).

Monday, March 16, 2009

The Boys Are Hungry

Someone once said to me, “Be careful, the boys are hungry out there.” This refers to the theft of ideas on the Internet. If I have what I believe to be a winning electronic concept, I may develop several embodiments of the same. So last year I designed a “Super Simple Counter”. Embodiment A was published in a British magazine, Embodiment B was published on this blog (see http://thomasscarborough.blogspot.com/2009/01/simple-counter.html), and Embodiment C was due to be published in Australia. Yet before Embodiment C could be published, someone "borrowed" Embodiment B, and had this published in Australia (the "borrower" has duly been paid for his efforts). I wrote immediately to my Australian editor: “May I withdraw [Embodiment C]?” The reason is that I wouldn’t want Embodiment C to be seen as a copied concept (a copy of the copy)! OBSERVATION: Sometimes there are “straight copies”, and sometimes there are minor modifications -- as simple, sometimes, as substituting equivalent parts. In this case, my design was creatively modified, although it was plain to see that it was a copy. See http://thomasscarborough.blogspot.com/2007/09/disco-craze.html for a visual example of a copy of one of my designs. It’s not the same, but you'll see that it’s a copy.

Friday, March 13, 2009

Crime Collage


Here’s a collage of material damage in and around the Church. From top left, clockwise: a battered down door, a stolen wheel, a hacked out copper pipe, and a missing garden plant. OBSERVATION: This is a small, random sample. Someone asked me whether it doesn't get me down. I said no, it doesn't.

Tuesday, March 10, 2009

Super Simple SONAR


My electronics posts have been popular. Here, therefore, is a “super simple” SONAR (designed by me). SONAR stands for SOund NAvigation Ranging. It is a technique which is used to determine the distance and direction of objects by acoustic means -- usually in water, but also in air. The SONAR described here has the most basic functionality -- it simply reports the existence of an object up to a few metres’/yards’ distance. It would, for example, shriek when a reversing vehicle approached a wall (X1 and X2 would be mounted just far enough apart NOT to shriek until the vehicle was near the wall). Or X1 and X2 would be mounted on opposite sides of a closed door -- thus the circuit would shriek when the door was open. Or X1 and/or X2 could be placed underneath an item, to shriek when the item was lifted. OBSERVATION: The circuit relies on acoustic feedback. IC1 is a sensitive amplifier. Both X1 and X2 are piezo sounders (discs, mounted in plastic housings) without internal electronics. X1 functions as a "microphone", X2 as a "speaker". Ideally, X1 and X2 will be identical, to encourage feedback at their resonant frequencies. Piezo tweeters may also be used, although these are expensive. C2 determines gain (amplification). First try the circuit without C2. If C2 is, say, 10μ, the circuit’s sensitivity will be greatly increased. C3 is necessary to limit output current. The circuit would ideally be run off a 12V DC plugpack power supply. You may click on the circuit to enlarge it. Click on the "Electronics" category top left to follow the electronics trail on this blog.

NOTE: You may re-publish this design, on condition that you acknowledge the designer (Thomas Scarborough) and this blog (http://thomasscarborough.blogspot.com).