Unusual functions of cheap parts
in [Design]
|
Prev: Op Amp Calculations
Next: 6v & 90v DC Power supply
From: John - KD5YI on 26 Nov 2005 15:51 Jim Thompson wrote: > On Fri, 25 Nov 2005 22:13:38 -0500, Phil Hobbs > <pcdhSpamMeSenseless(a)us.ibm.com> wrote: > > >>Si Ballenger wrote: >> >> >>>>I would put a 100 watt lamp in series thereby limiting the current. I >>>>would shave the ends down to points so they heated up rapidly. I put >>>>them into a hollowed out fire brick and made a cheap furnace. Of course >>>>don't look at it; it's like looking at the sun. >>> >>> >>>The current limiter I saw used a glass pie pan with pieces copper >>>metal on each side with salty water as the electrolyte. It would >>>start to steam some when in operation. The furnace was a small >>>clay flower pot with holes in each side with the carbon rods >>>sticking inside until they touched. >>> >> >>As a boy, I used an electric teakettle as a ballast for a two-D-cell carbon >>arc lamp--worked great. >> >>Cheers, >> >>Phil Hobbs > > > I've used a light bulb in series with a rectifier to charge a car > battery (just make sure that line ground goes to chassis ground ;-) > > ...Jim Thompson Going the other direction, I used the elements from a toaster as a load to discharge wet-cell lead-acid batteries. It was a discharge/charge cycling test. John
From: Jim Thompson on 26 Nov 2005 15:53 On Sat, 26 Nov 2005 21:41:06 +0100, Winfried Salomon <wsalomontrashcan(a)t-online.de> wrote: >Hello Jorgen, > >Jorgen Lund-Nielsen wrote: > >[.....] >> 2N2369 for fast pulses. > >btw, do you know a standard complementary pnp-transistor for the 2N2369, >such like 2N3905 but with higher ft and less feedback capacitance? It >seems that the manufactorers have almost no data on their internet pages. > >mfg. Winfried A 2N2369 is a gold-doped NPN, gold-doped to kill storage time and improve recovery from saturation. I don't recall any PNP device with gold-doping... or the equivalent. ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
From: Henry Kiefer on 26 Nov 2005 18:02 As a youngster I played with TTL DIP-ICs in my chamber and my parents next room felt that the tv was going crazy. The pins had long wires... - Henry <skavanagh72nospam(a)yahoo.ca> schrieb im Newsbeitrag news:1132928901.255333.129630(a)g43g2000cwa.googlegroups.com... > As an addition to the various mentions of common diodes as varactors > there is a well publicized British design for a frequency tripler that > will put out 2 watts at 1.3 GHz and uses five 1N914's in parallel. > > I once built an HF transceiver that used CMOS logic chips for all > functions except an audio low noise amp and a voltage regulator...with > further thought those two could likely be done with CMOS logic too. >
From: Henry Kiefer on 26 Nov 2005 18:04 The 4007 is the classic crystal oscillator circuit. Don't forget the temperature characteristics! - Henry "Murray" <me(a)erewhon.net> schrieb im Newsbeitrag news:43884488$0$12455$5a62ac22(a)per-qv1-newsreader-01.iinet.net.au... > Frithiof Andreas Jensen wrote: > > > "Henry Kiefer" <otc_friend(a)gmx.net> skrev i en meddelelse > > news:4385b3b1$1$27887$9b4e6d93(a)newsread4.arcor-online.net... > > > > > >>Do you know of other interesting devices or circuits good for misuse? > > > > > > Unbuffered logic gates can make a really bad but still useful analogue > > amplifier by adding feedback and bias. > > > > > E.G the CMOS 4007. See the old handbooks for a '100dB > amplifier' based on a RCA chip - there was a wiring > error in that old description - IIRC it was 3800? - > whatever, the 4007 is the same chip. > > Murray vk4aok
From: Henry Kiefer on 26 Nov 2005 18:10
There even exists LED specially taylored to the needs of doing duplex operation. - Henry "Frithiof Andreas Jensen" <frithiof.jensen(a)die_spammer_die.ericsson.com> schrieb im Newsbeitrag news:dm6msq$bvk$1(a)news.al.sw.ericsson.se... > > "Henry Kiefer" <otc_friend(a)gmx.net> wrote in message > news:4385b3b1$1$27887$9b4e6d93(a)newsread4.arcor-online.net... > > > Do you know of other interesting devices or circuits good for misuse? > > LED's work both ways, as a light emitter and a photodiode. > > The inbuilt colour filter can be used to distinguish between Grass and Not > grass f.ex. by comparing output from a red and a green LED using white light > as illumination. > > Back when fiber was ex$$$pensive one often saw clever circuitry using two > transmitters to form a duplex connection over a single fiber. > > The USD 10 solar powered garden lamps will, with a little persuation, yield > a nice solar cell well below the price of a similar unit in the shops - > and - two 600 mAh NiMh batteries and a grotty circuit for switching the LED. > > |