Search found 40 matches
- Sun Aug 14, 2011 1:10 pm
- Forum: General Discussion
- Topic: Salvaging a $21 Radio Shack Soldering Iron
- Replies: 12
- Views: 32549
Salvaging a $21 Radio Shack Soldering Iron
I have the Radio Shack variable-temp soldering iron 64-094. RS does NOT sell a replacement tip. One review on their website says it can be special ordered, but alas, it cannot. Rather than admit I'm out $21, is there a source for the replacement tip out there anywhere? It's the same size as their he...
- Tue Apr 19, 2011 9:22 am
- Forum: General Discussion
- Topic: 6V Sealed-lead-acid battery charger
- Replies: 3
- Views: 2570
6V Sealed-lead-acid battery charger
Okay, somehow my Science Olympiad team's $400 digital scale had blown its charger circuitry. It uses a 6v, 1.2 SLA battery. Right now, the "fix" involves putting two batteries (we have a spare) in series across a 12V el-cheapo Hargior Freight trickle charger. I found a bunch of charger cir...
- Sun Feb 06, 2011 9:37 pm
- Forum: General Discussion
- Topic: Upping LM781 Output Voltage
- Replies: 3
- Views: 2502
Upping LM781 Output Voltage
I have a small pile of LM7815 regulators. Can I take advantage of the .6V silicon voltage drop and add a few diodes between the ground pin and actual ground to raise the output voltage? I need to drop 24v from two sealed lead-acid batteries down to about 18 volts or so; regulation isn't critical and...
- Tue May 04, 2010 7:53 pm
- Forum: General Discussion
- Topic: PIC FreqOut to a speaker
- Replies: 4
- Views: 2538
Re: PIC FreqOut to a speaker
FINAL RESULTS!!!!! State Tournament was this past Saturday (May 1). They had found a 100-ohm speaker, and had serout drive a 2N2222 transistor. Worked great. Gotta admit, it was the crowd favorite. There was a 6-way (or more; still waiting on factual details) tie for first, and when broken, my kids ...
- Wed Apr 21, 2010 11:09 am
- Forum: General Discussion
- Topic: PIC FreqOut to a speaker
- Replies: 4
- Views: 2538
PIC FreqOut to a speaker
Kids have their Parallax PIC playing the Chicken Dance. Oh Joy. Fortunately, with the transducer included in the kit, it's barely audible. Well, they want it amplified somehow. WHAT AM I ASKING?!?!?!?! Is there a simple way to hook up a transistor like a 3904, 2222, or 4401 (which I have) withy one ...
- Wed Dec 09, 2009 10:07 pm
- Forum: General Discussion
- Topic: Need a transistor-less, IC-less photocell circuit
- Replies: 21
- Views: 10073
Re: Need a transistor-less, IC-less photocell circuit
Using 6 D cells (9V), a 1.5v pager motor, some photocells on sale from Electronics Goldmine and a breadboard it was a breeze for Johnny Boy to figure out the circuit. Took him more time to solder some wire to the tiny pager motor that it did to set up the photocells. three photocells in parallel dro...
- Sun Nov 15, 2009 7:16 pm
- Forum: General Discussion
- Topic: Need a transistor-less, IC-less photocell circuit
- Replies: 21
- Views: 10073
Re: Need a transistor-less, IC-less photocell circuit
Thanks for all the help! Leaning towards the many-CdS-cells-in-parallel route. One unfortunate thing; due to "rules lawyers", everything is spelled out to an extreme-- even commas matter. Also, since I used to be a National Supervisor for this very event, anything my kids do is scrutinied ...
- Fri Nov 13, 2009 11:03 am
- Forum: General Discussion
- Topic: Need a transistor-less, IC-less photocell circuit
- Replies: 21
- Views: 10073
Re: Need a transistor-less, IC-less photocell circuit
I'm wrapping up a two-day nature camp with 30 middle school kids.
Pray for me.
Yerry
Pray for me.
Yerry
- Tue Nov 10, 2009 7:42 pm
- Forum: General Discussion
- Topic: Need a transistor-less, IC-less photocell circuit
- Replies: 21
- Views: 10073
Need a transistor-less, IC-less photocell circuit
Without naming the organization, a HS-level science organization has a Rube Goldberg machine event, and one of the steps is a real stumper: Use current through a photocell to turn on a small motor. The motor must perform the next step (read: actually do something) Here are the killer clauses: 10V ma...
- Tue Dec 16, 2008 10:21 pm
- Forum: General Discussion
- Topic: 1,000 LED Sequencer
- Replies: 45
- Views: 29262
- Thu Jun 19, 2008 12:42 pm
- Forum: General Discussion
- Topic: Simple DC Power Supply Schematic Needed
- Replies: 38
- Views: 19568
- Wed Jun 11, 2008 2:27 pm
- Forum: General Discussion
- Topic: stumped on a 555/556 project.
- Replies: 22
- Views: 9127
- Sun May 04, 2008 4:35 pm
- Forum: General Discussion
- Topic: Very Low-frequency Oscillator to Power Tr-Color LED's
- Replies: 1
- Views: 1872
Very Low-frequency Oscillator to Power Tr-Color LED's
I'm building some "nighttime" special effects for my Super Mouse Trap module. I took an old vacuum tube, removed the pins and drilled the holes out to fit a 5mm LED. I stuck a few monochrome LED's in it, and by varying the voltage got some interesting effects from the colors reflecting off...
- Fri Apr 11, 2008 6:22 pm
- Forum: General Discussion
- Topic: TV Digital Converter Box Coupons & Sales Tax
- Replies: 7
- Views: 5578
- Tue Apr 08, 2008 4:48 pm
- Forum: General Discussion
- Topic: ZERO to ~15v adjustable regulator part/schematic?
- Replies: 7
- Views: 3694