Search found 40 matches

by Yerry
Sun Aug 14, 2011 1:10 pm
Forum: General Discussion
Topic: Salvaging a $21 Radio Shack Soldering Iron
Replies: 10
Views: 1978

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...
by Yerry
Tue Apr 19, 2011 9:22 am
Forum: General Discussion
Topic: 6V Sealed-lead-acid battery charger
Replies: 3
Views: 1075

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 circuits that...
by Yerry
Sun Feb 06, 2011 9:37 pm
Forum: General Discussion
Topic: Upping LM781 Output Voltage
Replies: 3
Views: 934

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...
by Yerry
Tue May 04, 2010 7:53 pm
Forum: General Discussion
Topic: PIC FreqOut to a speaker
Replies: 4
Views: 860

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 ...
by Yerry
Wed Apr 21, 2010 11:09 am
Forum: General Discussion
Topic: PIC FreqOut to a speaker
Replies: 4
Views: 860

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 ...
by Yerry
Wed Dec 09, 2009 10:07 pm
Forum: General Discussion
Topic: Need a transistor-less, IC-less photocell circuit
Replies: 21
Views: 3496

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...
by Yerry
Sun Nov 15, 2009 7:16 pm
Forum: General Discussion
Topic: Need a transistor-less, IC-less photocell circuit
Replies: 21
Views: 3496

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 to an extr...
by Yerry
Fri Nov 13, 2009 11:03 am
Forum: General Discussion
Topic: Need a transistor-less, IC-less photocell circuit
Replies: 21
Views: 3496

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
by Yerry
Tue Nov 10, 2009 7:42 pm
Forum: General Discussion
Topic: Need a transistor-less, IC-less photocell circuit
Replies: 21
Views: 3496

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...
by Yerry
Tue Dec 16, 2008 10:21 pm
Forum: General Discussion
Topic: 1,000 LED Sequencer
Replies: 45
Views: 8967

dONE WITH TWO COMPONENTS!

One current limiting resistor.

One single-pole, thousand-throw switch.



:grin:
by Yerry
Thu Jun 19, 2008 12:42 pm
Forum: General Discussion
Topic: Simple DC Power Supply Schematic Needed
Replies: 38
Views: 10651

I happen to help friends down in Fla with their Garden Railroad. Here's what's up, plus a few questions that actually matter: The DC trains run typically 2V-12V/14V. Most transformers output higher, like 16V or even 18V, on the understanding that the extra voltage is "headway" for the track sections...
by Yerry
Wed Jun 11, 2008 2:27 pm
Forum: General Discussion
Topic: stumped on a 555/556 project.
Replies: 22
Views: 3918

Easier way:

Google-ize "Cogeco" and "555". You'll get a Canadian model-railroad electronics site. Click on 555 circuits. Go most of the way down, and you'll find a pair of circuits, same image, that activate when the trigger input has been continuously activated for a specified amount of time.
by Yerry
Sun May 04, 2008 4:35 pm
Forum: General Discussion
Topic: Very Low-frequency Oscillator to Power Tr-Color LED's
Replies: 1
Views: 832

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 the chrom...
by Yerry
Fri Apr 11, 2008 6:22 pm
Forum: General Discussion
Topic: TV Digital Converter Box Coupons & Sales Tax
Replies: 7
Views: 2831

But it wasn't a sale at a lower price. Your $40 coupon was a subsidy. The store didn't charge ten bucks, it charged fifty. sales tax is based on the price of the item sold, and now how much you paid in cash.
by Yerry
Tue Apr 08, 2008 4:48 pm
Forum: General Discussion
Topic: ZERO to ~15v adjustable regulator part/schematic?
Replies: 7
Views: 1597

]But how will you know that it's working correctly; outputting zero volts instead of blowing itself up and outputting nothing?
:razz: