Luxstar's Scratch Pad





Introduction: Luxstar's Scratch Pad

Welcome to my scratch pad. This is where I post ideas that are not quite ready to have their own instructable and also works in process. They are not done yet but I still would like to share them. Each step is one idea or project. Only one step per idea. Steps / ideas /projects will be added from time to time. Feel free to rip off any ideas posted here and do your own really good instructable.

Step 1: Macgyver Emergency Electric Heat
Step 2: Recharging a Non-Rechargeable Alkaline Lantern Battery

Step 3: Desk Top Hand Crank Mechanism for Micro- Generator

Step 4: Earth "Radio"

Step 5: Cooking With 3 Candle Flames Instructable Has Been Updated

Step 6: MPSA18 Single Transistor Preamp. High Gain

Step 7: Super Long Run Time Laser Pointer. Excellent Decoys

Step 8: Simple IBM Compatible PC Printer Port (LPT1) Power Interface

Step 9: Two Stepper Motors – Force at a Distance

Step 10: Yak Bak With Auto Play Timer, Pitch Control, and C cell Extended Run Time

Step 11: Audio Modulated Flashlight

Step 12: Photo Transistor / Lens Assembly for Receiving Light Modulated with Analog Audio

Step 13: .Convert Eveready EVEL 152S Flashlight from Spot to Flood

Step 14: Light Wave Communication: Notes for Class Room Demonstrations

Step 15: Light Detector / Alarm Using a Solar Lawn Light

Step 16: Pics

Step 17: Ultra Cheap Project Boxes and Switches

Step 18: A Typical LED Light Bulb. Why Don't They Last Longer?

Step 19: Convert an Old TV Remote into a Laser Pointer

Step 20: Connecting Land Line Phones Directly together Off Grid ( with the Telephone Company and Power Grid Down)

OK to link:

Step 1: Macgyver Emergency Electric Heat

I wanted to run some tests with household appliances that produce heat to see how much heat would be produced if they were powered by 12 volts (like from a small solar panel). The toaster oven did not work very well but halogen incandescent light bulbs worked pretty good. As you can see from the picture I cracked open a common halogen bulb to reveal the actual smaller bulb inside. by drilling a smaller hole than the size of the bulb you get a water tight seal. This set up did warm up water after about an hour but did not come close to making it boil. The intact bulb makes a fine hand warmer. I tried connecting a 240 volt 4000 watt water heater element to 12 volts. I got about 15 watts of heating which worked well to melt ice. The element has almost completely melted 4 ice cubes while the control group of ice cubes have not melted much at all. This should work fine to melt snow for drinking water. The element heated a glass of water to just under 120 degrees F. A 20 watt or larger solar panel should work fine for about 4 - 6 hours a day melting snow or just heating up some water which would be useful for preheating water to save on propane when cooking. See also step 5: Cooking with 3 candle flames.

Step 2: Recharging a Non-Rechargeable Alkaline Lantern Battery

I ran a 6 volt alkaline lantern battery in one of my modified flashlights continuously for some ridiculously long time (600 plus hours I think). So I wanted to try recharging it using two gutted solar lawn lights (no electronics left but the solar cells). The two pictures are from my electric skylight instructable. The circuit for recharging the battery is almost the same as the skylight circuit. The LED is replaced by a blocking diode such as a 1N4001. The battery takes the place of the resistor with the positive terminal of the battery connected to the positive wire on the solar cell. The circuit puts out slightly over 6 volts with no load in direct sun light. The maximum current is about 30 milliamps. This seems safe enough since the maximum heating effect would be less than 1/4 watt. Even though I was pretty sure there was no chance of the battery exploding (some batteries have a warning like do not recharge, may explode) I still put the battery in an ammo can, There was no explosion or leakage. It took many days to recharge but it did work.


The idea of recharging a non rechargeable alkaline is not new. Check out this article:

Step 3: Desk Top Hand Crank Mechanism for Micro- Generator

I did some testing of different motors with the setup pictured above to see which motors would work well as a generator. The shaft of the motor or the pulley on the shaft of the motor is made to make contact with the spinning wheel. All the motors tested worked but not as well as I would have liked so at some point in time I need to buy a bicycle light / generator kit and do some more testing. Ultimately I would like to see how well this setup can recharge one of my 400 farad super capacitor flashlights. I have done some testing with an old DC floor buffer motor with planetary gear box. It is massive. My recollection is that I got the capacitor back up to half charged (the easy half) in about a minute. I would like to do the same thing but with a smaller set up.

The construction of the crank mechanism:

The upright 2 x 4 wood post is attached with screws through drilled and countersunk holes. The 1/2" wheel shaft has a cap that is made for wheel shaft end which is hammered on. The 8" wheel (with sealed bearing) is spaced from the post with oversized plastic nuts. A PVC pipe would have worked also. The shaft connects to the post though an undersized hole (it was hammered on) The handle a small diameter PVC pipe with a bolt through it. The handle assembly is connected through a hole in the wheel hub (could have been through the solid tire). There are washers and nuts on both sides of the tire to secure the bolt to the wheel. Since the wheel is dense hard plastic without much flexibility (firmer than a bicycle tire) The final assembly would have the generator shaft making contact to the wheel from above (12 o'clock position). The generator would be attached to a narrow piece of wood and the other end is attached to the top of the post with a small hinge so the generator shaft can ride freely on the top of the tire. A weight is added to the narrow piece of wood to facilitate good contact between the generator shaft and the tire.

Step 4: Earth "Radio"

I'm not sure if this has every been done before. Several years ago I got this idea that if you played a speaker level audio signal into the ground with several feet between the two wires you could pick off the signal anywhere in between and amplify it. It works. Here is what I did:

The "Transmitter"

I ran wires from the back of one speaker output of a 50 watt amplifier into the back yard. I ran one wire to one side of the yard and the other to the other side. The wires were connected to plated steel tent spikes and hammered into the ground. I played an audio recording through the amp at full volume.

The "Receiver"

I screwed two (about 3" long) plated steel deck screws about 6" apart into a piece of wood. One screw had the ground wire from an audio cable connected to it. The other screw had the center wire of the cable connected to it. The other end of the audio cable was plugged into a battery operated amplifier. I attached a dowel to the piece of wood to use as a handle.


Anywhere I stuck the spiked end of the wood into the ground resulted in plenty of clear audio through the speaker of the battery operated amp. It was not high fidelity but there was plenty of volume.

Future Testing:

I hope to test this over a larger area. Perhaps a public park in the early morning hours. The amplifier will probably be a car amplifier. If Higher gain is needed I will run the received signal through a battery operated preamplifier first. My first attempt worked so well I believe there would be no problem receiving signals with over a mile in between the wires. I will have to limit my testing to about 1000 feet. since I have a couple f spools with at least that much wire. Soil conditions will be a factor but it should be noted that I almost never water.

Step 5: Cooking With 3 Candle Flames Instructable Has Been Updated

Cooking With Three Candle Flames has been updated. Step 8: "Using Candles for Survival Heat" has been added. It is the full text from my article "A Candle Flame: Survival Heat x 3". This article deals with ways to stay warm in an apartment or house in sub-freezing weather with no utilities. Did you know that 3 candle flames can produce about 240 watts of heat?

Here is the link to the instructable:

Step 6: MPSA18 Single Transistor Preamp. High Gain

The switch is turned on when powering a condenser microphone. The circuit works fine from about 3 volts to over 12 volts.

If you need more volume than what you are getting from my condenser microphone power supply, this should take care of the problem. Here is the link to the power supply (battery operated):

Step 7: Super Long Run Time Laser Pointer.

I bought a pack of 10 laser diodes on ebay a few years ago. As of today you can get 10 red laser diode modules with shipping included for $4. So batteries are what will cost money in the long term to power these. The variable resistor seen in the right in the 2nd picture is to decrease the spot a little since it was brighter than I wanted for my application. The also is used to crank up the brightness as the batteries wear down. The run time is ridiculously long.

Step 8: Simple IBM Compatible PC Printer Port (LPT1) Power Interface

Pictured above is an interface box to use the printer port on an old IBM compatible computer to run 8 channels of Christmas tree lights. Due to its modular design it can easily be re-tasked for multiple functions by
wiring up different wire harnesses that can be plugged into the 9 pin connector (output connector to 8 channel light harness).

I have misplaced my schematic so for now, from memory, here is how it runs the lights: The adjustable power supply is set at little under 24 volts. Each of pins 2-9 of the 25 pin connector are connected to its own current limiting resistor. The value is selected to power the LED inside each optocoupler. Consult the data sheet for the optocoupler you use to determine the current to run the LED at. I believe I am running mine at about 10 milliamps each. The maximum voltage of the device needs to be rated above the voltage of the lighting circuit. The outputs of each optocoupler is connected to it’s own current limiting resistor and each resistor is connected to the base of a bipolar power transistor. The transistors I used (TIP152 ?) are overkill for this project but all the parts except the chassis and string of lights I hacked up were parts I had laying around. Depending on the voltage and current requirements of the circuits you are powering, you may be able to skip the power transistors and run the circuits directly off the optocouplers. Two 4 channel optocouplers would further reduce your part count.

The string of lights for each channel are 7 LEDS in series. I will provide a sample of source code (Borland for DOS) at a later date. Brief 5 volt pulses are available at pins 2 – 9 when any number between1 and 256 is sent via software to the LPT1 serial port. Since the output of the printer port is a very brief pulse each time a number is sent, it is necessary to send the same number several times to make it appear for even a 10th of a second. Therefore, the need for loops that run a predetermined number of times before going on to the next loop. For a series of complex patterns the loops are nested.

Besides channels of lights, it should be easy enough to run small DC motors, solenoids, valves, sonic transducers, mechanical relays to power anything. (or lasers from the previous step). Some applications may require the pulses to be smoothed out with a capacitor.

The printer port has an additional 5 pins that are signal inputs and 3 that can be used as an input or an output. In theory you could have one binary feedback channel for each output or two for four outputs such as “home and limit” slot type optical sensors as well as lever and plunger type micro-switches.

Pseudo random numbers are available by sending text and other of the lower 256 ASCII character set character by character to a loop. This can be hardcoded or read from files on the hard drive.

If you program in C then you know how easy it is to use a keystroke to assign a number to a variable

int a = getch();

and then use the value of variable “a” to call a function in the program. So several of the keys on the keyboard can be used to run various printer port subroutines. Controlling various motors, lights and other devices for various amounts of time or until a particular feedback signal is received. Since any of 256 combinations of the 8 channels can be selected any number of times, any combination of 8 devices or circuits can be run simultaneously or independently in various repeating or non-repeating patterns. Using only lower case letters and numbers 0 – 9, you can run 36 pre-programmed routines, some of which may be very short durations such as running a geared down dc motor for ¼ of a second. So the user presses one of the keys repeatedly until the motor turns the desired amount. Last of all, Characters can be used one by one from a text file to call the various functions. When a called function is complete, the next character is read from the file. This method could accommodate up to 256 different routines called millions of times in any order. These could be hard coded into the program but files are easier to edit and you could write any number of different files.

Think of the possibilities.

Since I made this out of scrap parts I had laying around and a really old computer, my actual cost was about $20 and a few evenings of time.

Step 9: Two Stepper Motors – Force at a Distance

Stepper motors are brushless direct current motors. DC motors with brushes will run as long as the motor is connected to a sufficient amount of voltage. Stepper motors must have pulses of voltage applied to the coils. Stepper motors have magnets and coils inside so turning the shaft will generate pulses of electric current. All of the stepper motors I have worked with have 4 wires or 6 wires. The 4 wire motors have half of the coils in the motor connected in parallel to two wires and the other half connected to the other two. Motors with 6 wires are wired the same way but the coils have center taps. In this application (connecting two motors together) the center tap wires are unused. When you connect two stepper motors together and turn the shaft on one motor, that motor sends pulses to the other motor and the shaft turns. This typically works much better than doing the same thing with DC motors with brushes. Depending on the size of the two motors, if you turn the shaft sufficiently fast, which is not very fast at all, you get about equal steps from the motor being driven. In other words one rotation from the driving motor will cause the driven motor to turn about one rotation. Larger motors tend to work better and have more torque. The motors in the picture are kind of small but still work. The mechanical motion from the motor you are turning can cause another motor to turn over long distances without using batteries or any other external source of power. The two motors can be connected together using 4 wire modular phone cable or CAT5 cable. The torque is much lower in this application than it is when used as intended but still should be useful for some light duty functions. Over the next few days I plan on doing some decoy testing. I should be able to knock a few things over or bang on a few things. Maybe rotate something. Just in time for Halloween.

I also will be testing a remote spot light sometime in the future. It works like this: You have a high intensity, narrow beam source of LED light such as the parabolic mirror and led assembly from a LED lantern flashlight. This is pointed straight up and can be remotely turned on and off. Directly above this a stepper motor with a mirror mounted at a 45 degree angle is pointing straight down. As the motor turns, the beam of light shoots out horizontally and can sweep left and right and turn 360 degrees as well as be turned on and off (one CAT5 cable with 2 wires left over. If this is a decoy, the assembly should be about waist high.

New stepper motors can be expensive. Surplus motors are comparatively cheap. Here is a source of all kinds of small surplus motors:

Buy at your own risk. Your results may vary.

By the way, you can run two stepper motors with one CAT5 cable or 4 regular DC motors. If your DC motors are always going to be running in the same direction (no switching of the voltage polarity) you can run 7 DC motors independently of each other with a common ground. Or you could run a stepper motor. Send audio to a speaker (or power some other sound producing device) and power up some LED lighting with no common grounds with one CAT5 cable.

Step 10: Yak Bak With Auto Play Timer, Pitch Control, and C Cell Extended Run Time

If you don't know what a Yak Bak is, Here is the link:

I bought a few of the original ones when they first came out about 20 years ago. This deluxe model has the following features:

Pitch control which works for record and play back.

Timer for automatic play back from about 2 second to 20 minutes.

Extended run time (months with 20 minute play back).

External microphone jack / audio in connector.

External speaker / Audio out connector.

Timer signal out connector to control other low voltage devices.

Standard Yak Bak record and play functions.

The Yak Bak originally ran on 4 button cell batteries (A76?) so C cells allow it to run a ridiculously long time. The sound quality and volume are improved with the larger speaker. I used to work at a company that made robotic equipment among other things. The engineering department made a large foam board mock up of a piece of robotic equipment in the corner of a large conference room. I recorded the sound of one of our products in motion and put the deluxe yak bak inside the mock up. It made multi axis motor noises every few minutes. I was unaware that there was going to be an engineering meeting that day. It was great fun for the engineers on that side of the room. Luckily the big boss was on the other end.

Step 11: Audio Modulated Flashlight

Here is a two for one project. You start out with the unmodified flashlight from this instructable:

This instructable shows you how to take a $5 flashlight and add a resistor to give it a 300 plus hour run time (more than double that with an alkaline battery). This audio modification will give you about the same run time but you can also run audio to it to modulate the beam of light for light wave communication. RadioShack used to sell a 600 ohm to 600 ohm transformer (see 3rd picture, wrapped in green tape). The DC resistance is about 50 ohms so it was perfect for limiting the current of this flashlight. Here is the link to a transformer that should work fine for about $2:

The RCA jack is wired to one side (primary or secondary) of the transformer. The other side is wired into the flashlight circuit in place of the resistor from the other instructable. A headphone / earphone level audio output works fine to modulate the beam. The beam of light can be turned back into audio with an amplifier circuit with any of the following connected to it: Photo transistor, CDS photo cell, solar cell. The photo transistor and CDS photo cell need to be powered in the circuit the same way you power a condenser microphone element. The solar cell will need a capacitor to block the DC component of the signal from the solar cell. A future step on the scratch pad will have a circuit using the LM386 amplifier chip that will work fine. The received beam of light can be concentrated using a lens or parabolic mirror to increase the signal strength. If the beam of light is shining on the side of a building, the signal can still be picked up with a lens and amplifier circuit. This means that the sender and receiver do not need to be line of sight. To increase the transmitting distance you may want to try a stronger audio signal and a more powerful flashlight. A preamplifier and an audio amplifier on the receiving side will also add useable distance.

So your very useful flash light can be used to send silent, non radio frequency signals.

Step 12: Photo Transistor / Lens Assembly for Receiving Light Modulated With Analog Audio

In a previous step we looked at modifying a flashlight so it could be modulated with audio signals and therefore transmit audio information over a light beam. Here is a simple assembly that uses a lens to concentrate light into a photo transistor. I used a photo Darlington for greater gain. The collector of the transistor is connected to the center connection of the connector. The emitter is connected to the shield connection of the connector. The transistor needs to be powered the same way you power a condenser microphone element. See this instructable for how to do that:

If too much ambient light causes the transistor to stop working you could put window tinting film over the lens. I have not had this problem. Never point this assembly at the sun.

My set up works great. Among other things I have listened to I have heard the wings of insects in bright sun light at 20 - 30 feet. Aircraft strobes are no problem. If the aircraft headlight is behind the prop, you can hear that although I may have been hearing sun light reflected off the prop. With the use of a preamp connected to an amplifier I was able to receive audio from a modulated laser pointer pointed at a transformer on a telephone pole. In other words, the laser was not pointed at the photo transistor assembly. I picked up the audio off the dot about 100 feet away. Greater gain can be achieved with bigger lenses.

Step 13: Convert EVEL 152S Flashlight From Spot to Flood Light

Text will be added later.

Step 14: Light Wave Communication: Hand Outs From Class Room Demonstrations

These are class room hand outs for some high school science class demonstrations I helped put together from about 20 years ago. The last two pages were added on the second time around doing demonstrations along with some new equipment. Some pictures to follow but not all equipment will be shown since they are currently missing.

Step 15: Light Detector / Alarm Using a Solar Lawn Light

I decided to do my initial testing with part I already have. The light sensor is a solar lawn light with all the parts removed and only the solar cell remaining. I tested two piezo buzzers but only one worked well. Make sure the buzzer you use does not require a driver circuit. Also make sure the working voltage goes down to 3 volts. The first schematic with no VR (variable resistor shows a 2N4400 NPN transistor. I also tested an MPSA14 which worked a little better. The addition of the VR will make the sensitivity adjustable to stop the beeping from ambient light. I did some testing with a 100K VR as well as fixed resistors. a 500k - 1M VR would be optimum. The circuit works well detecting low power flashlights. It detected a 25 lumen flashlight at 40 feet. The circuit was tested a 3 volts and 6 volts. Due to differences in solar cells and piezo buzzers, your results may vary. The next tests will be with car headlights. I will be making a permanent unit soon.

Step 16: Pics

Here are a few of the latest original pictures and some stored pics

Step 17: Ultra Cheap Project Boxes and Switches

Quite often the most expensive parts I use to build an electronic project are the enclosures and switches. The electrical junction box and toggle switch wall plate will most likely be the enclosure for my next battery operated LED desk lamp / task light. In case you are not familiar with the metal box pictured above, this is a an electrical junction box that is used as an enclosure for a light switch or electrical outlet. Every light switch and electrical outlet in your house has one of these or one like it inside the wall. These single gang (big enough for one switch or one dual outlet) are dirt cheap. I checked the prices on the Home Depot website today. The least expensive components I found were as follows:

Single gang drawn handy box (just like the box above): $0.94

Single gang blank (no switch or outlet cut outs) wall plate (plastic): $0.47

Single gang blank (no switch or outlet cut outs) wall plate, stainless steel: $1.69

Single gang toggle switch wall plate (plastic): $0.28

15 amp single pole toggle switch (not pictured but like the light switches in your house): $0.69

So you can buy the two pieces that make up the enclosure and an on / off switch for under $2.00.

My desk lamp will be powered by a D cell battery so the 15 amp toggle switch will be too big. I will be using a miniature toggle. This is why I bought the blank wall plate.

Updated: I have added more photos. I spray painted the junction box. I drilled holes in the switch plate and installed and wired them to the D cell holder in the junction box. The next update should include the DIY flexible goose neck cable probably made from an RCA cable and a piece of 10 or 12 AWG solid copper wire (house wiring). One end will plug into the RCA jack on the switch plate. The LED module plugs into the other end. This battery operated "desk lamp" is different than my other "desk lamps". On this one the circuit that steps up the voltage from about 0.5v - 1.6v up to about 3.6v is external. This is because Energizer/Eveready did such a good job on the flashlight I removed the board from that I was able to use it as is. The circuit and LED combination are about perfect. it's really bright. The flashlight is easy to hack and it is cheap (about $5 for a two pack). The package claims 60 hours run time. I'm not sure if that's 30 hours for each flashlight or 60. I will have to test to find out. Model EVEL152S. Get the ones that are fully enclosed in the packaging. This latest version has click on / click off switches. Earlier versions which are still being advertised by some on line sellers appear to be slide switches which are not as reliable. Plus I have not tested the earlier version. The earlier version of the two pack has the lower part of the two flashlight hanging out of the package.

Updated: I added a photo of a part of a light bulb taped to the energizer LED assembly.

Updated: After 72 hours the flashlight is still going with the junky carbon battery supplied with the flashlight. It is dimmer but still a useful amount of light. I will keep running it and update again. The run time should be about twice as long with an alkaline D cell.

Step 18: A Typical LED Light Bulb. Why Dont They Last Longer?

I recently did an article titled "☼ The 30 Year Light Bulb, Where Can I Get One?"

Here is the link:

I removed the plastic "bulb" part of the assembly to do some testing. I discovered that this light has 10 SMT LEDs. The light is much brighter without the translucent plastic part so it was definitely not a waste of the light bulb. I lust need to cover the exposed solder connections in the middle of the assembly to insulate the exposed 62 volts. The cover is being tested on a low power, low voltage light (see second picture).

Step 19: Convert an Old TV Remote Into a Laser Pointer

If you are a wire head like me you probably have a few old remote controls from appliances that pooped out long ago, Those appliances have been stripped of any parts you think you might use some day. Here is a list of things you can turn an old remote into.

1. Laser Pointer

Replace the infrared LED and replace it with a laser diode. I got mine for dirt cheap on ebay. I checked today's deals and there was 10 laser diodes with wires for about $8 and another one, 10 laser diodes with wires for about $4. Both were with free shipping. I cant remember how much I paid but it was one of these deals. So for less than a dollar and less than an hour of my TV watching time I made the Laser pointer pictured above, The hardest part was breaking into the enclosure. Some of these slide apart after you remove one or two screws and some snap apart with some prying.

The pluses:

Long battery life as this runs on two AA batteries and the laser pulses on and off at about 4 -5 times per second. Cheap (under a dollar).

Novelty: how great will it be to bring this laser pointer to your next department meeting at work for your power point presentation. Bring a high back leather office chair as well.


It blinks.

It is slightly dimmer than some other cheap laser pointers.

2. Flashlight,

Replace the Infrared LED with visible light LED. It will actually be a flashlight because it blinks on and off when you press a button.

3. Since the Infrared LED is being modulated at an audio rate you should be able to replace the LED with a small speaker. When you press a button it should go "Beep beep beep" rapidly. You can point it at people and press a button. When they ask you what you are doing you can say "I'm turning down the volume" or "I'm changing the channel".

Step 20: Connecting Land Line Phones Directly Together Off Grid (With the Telephone Company and Power Grid Down)

Diagrams and more text to follow soon.

You can easily connect two or more land line telephones together and power them with batteries. You and the folks next door can stay in communication by telephone with no electrical power and no local phone service. Make sure the land line phones you use are not the cordless type. The ones that only have a connection to the phone line are powered off of the phone line and do not require an AC adapter. These types of phones have no polarity so you don't have to worry about positive and negative connections.

Step 21: Next "Future" Project


Government priorities if the grid goes down: (in order of highest to lowest)

Continuity of government(s).

Attack / Defense against the originators of the attack(s)

Prevention of nuclear power plant melt downs

Repair of the power grid.

Repair of other essential parts of the infrastructure

Workarounds for the essential parts of the supply chain

(You are here) Provide aid to people in need (You are here)

Not that I disagree. I believe this is just reality.

Have you considered any personal emergency preparations?


appears to be, the person on the video seems to be strongly implying that prepping will be a really good idea including simple electronic and two way and short wave radios.

Hopefully since this is on the paranormal category someone can point out the specifics of why this is or is not a message from the future.



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interested to see you could actually recharge the cell. What chemistry was the cell if you remember? Any idea what sort of capacity it had from the recharge? Other projects were interesting too, thanks for throwing them up