Picture of $3 Emergency Solar Radio

In honor of all my good friends still over in Japan I've decided to create an Instructable for a $3 Emergency Solar Radio. It's a great thing in case of tsunami, nuclear melt down, or zombie invasion. Plus it's really cute when put into an Altoids tin.

My plan is to send this as a (slightly) joke birthday gift to a good friend of mine living in California, who just so happens to be freaking out about possible nuclear clouds. This will also be really nice for her when she starts going camping again this summer.

The design is very simple and only takes about 45 minutes to put together, less if you know what you're doing.

If you'd rather not make one yourself, I'll probably be throwing up a couple completed ones as well as most of the parts over at my website

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Step 1: What you need

Picture of What you need

I bought all the supplies I needed from my local $1 Store. (If in Japan, a 100 Yen store.)

To buy:
1x FM Radio
2x Solar Garden Light
1x Diode ($1 for 100 of them online, or take one out of any random junk pile)

If your local $1 Store isn't as cool as mine, you can probably find these things locally, online (like at my website, or from a trash bin.

Soldering Iron
Wire Strippers

Altoids Tin
Hot Glue
Mini Speakers ($1 Store, or take apart old headphones)

Support Me By Buying Some Parts...

If you can't find solar cells or cheap AAA batteries, I have quite a few on my website The same solar cells I use to make my Solar Cockroach would work great for this project. You could also slap on a bigger, more powerful cell onto the outside of the tin like these nice 4.5 volt cells.

I also some AAA battery holders and very cheap AAA batteries for sale that have a much higher capacity than the ones you'd find in your average solar light.

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I could (almost) make one of these following these instructions. I even have everything I need already. I was going to say except for the diode, but odds are there are some floating around here somewhere...

Just one question: Why do you have to throw the solar cell away if you break off the solder point? Can't you just re-solder it? I know this was already asked, but I don't see an answer, and I was wondering the same thing.

JoshuaZimmerman (author)  ThisIsMyNameOK24 days ago

With these type of cells if you break off the solder point, then there is no way to make a connection. If you use better solar cells you'll have an easier time. I was just using super cheap recycled $1 Store solar cells. Spending $5 on a better solar cell will make life a lot better.

Ah... I see. Thank you for your reply. I know nothing about these kinds of things and it just seemed like it was wasteful to throw it away.

klmyles1 month ago

Would a Digitally Tuned radio work??

(see this one I found -

JoshuaZimmerman (author)  klmyles24 days ago


christina.liittle made it!3 months ago



Super well done!

Skeleton key97 made it!11 months ago

i made it!!!!!! hahaa. its easy enough

JoshuaZimmerman (author)  Skeleton key9724 days ago


wazy8011 year ago
why do you have to drill on step 7?????

To make a hole for an earphone jack

Oh,my radio is the same as yours.

ishiyakazuo8 months ago

Just FYI, the reason that this works and receives a signal through the Altoids tin is because the headphones are the antenna. If you use speakers, you might need a separate FM antenna. Hope this helps.

kfrancis919 months ago

If you break off the solder point from the solar cell, couldn't you just solder it back on?

josuchav11 months ago

you misspelt goggles

ajensen2711 months ago
found 2 separate lights around the house. one has a 2/3 aa battery and its panel puts out 1.2v and the other has a AA battery and its panel puts out .95-.97 volts sitting under 40w bulb(it was night out). which panel do i use and how many. also do i need the diode?
Kirbsome!3 years ago
Quick tip:
When buying solar powered lights for this, look for blue solar panels.
They are usually higher quality than the dark brown ones.
thanks good to know
JoshuaZimmerman (author)  Kirbsome!3 years ago
Very true. Those CIS are dark brown and very high quality...
This has got to be one of the single most coolest things on instructables!
wazy8011 year ago
what kind of tap do I use o step 8???
Nhoj161 year ago
I just began making this when I realized I'm out of diodes. Will it still function without one?
Nhoj161 year ago
Cool project! I think I have all that I need to make this laying around so I'll definitely do it.
Jacky P1 year ago
What diode do I use?
i suggest a schematic diagram for the project. please to make things simple
Whatat does the diode do in the circuit? Just curious
Orkekum2 years ago
awesome idea and well written, i can buy cheap radio with a scan button and a return one
JoshuaZimmerman (author) 3 years ago
Just because I'm a teacher doesn't mean that I'm not human.

With feelings to be hurt...

teachers are awesome c:
deanes2 years ago
Altoid tins are neat, but maybe an easier more practical project would be to just add the charging panels directly to the radio case? Or, maybe the panels glued to a plastic pocket-shaped sheet and connected by a sturdy wire to the radio battery compartment. Then you would have a solar charging case for the radio.
JoshuaZimmerman (author)  deanes2 years ago
Probably, but this is rather bare bones. Plus cute. You gotta factor in the cute aspect.
DAND3 years ago
What type of diode did you use?
static DAND2 years ago
 The current carrying capability, the voltage rating and the voltage drop across the diode are considerations. Too much current can harm the diode, too much over voltage drop, the batteries may not fully charge. Nominal figures; for the silicon diode used here is .7 V, for the Schottky diode it's .2 V. In most solar application the Schottky is preferred, but one can't walk into radio shack and buy one. In low powered projects like this, it's easier to add an extra salvage solar cell, and used the more readily available silicone diode. No precision is required on the voltage rating here as long as it's higher than the battery voltage, the voltage rating is important if the diode will see a reverse bias as part as normal desired operation.
JoshuaZimmerman (author)  DAND3 years ago
1N914. Very common. You can find them everywhere.
Thanks for the great instructables!
quick question
Are there any differences if you use a 1n914, a 1n4005 or a 1n5819?
JoshuaZimmerman (author)  earm993 years ago
1N914 us just really really common and has a low voltage drop. It's very handy for low voltage low current systems like in this one.

Google the other diodes and check the voltage drop. They probably would work fine for this kind of setup.
Subo692 years ago
if you were to use capacitors instead, which one would you use?
JoshuaZimmerman (author)  Subo692 years ago
Well you'd want some super capacitors. Ones that have 1F or more of power at around 3V.

Actually the best approach would be to get a couple of 1F 5V super caps and hook them up in Parallel. (5V so that you don't overcharge the caps, and can then use a 4V or 4.5V solar cell with the project.)

But you'd need several of them to be on the safe side. Really 3 or 4 if you want to use the radio out of the sun.
This reply is directed more to those that will read the comment made by the author than it is to the author. As science teacher none of the following shouldn't be new to him. F Farad is not a unit of power.  A capacitor can't be overcharged, but is susceptible to damage from over voltage.  Following the author's suggestions here  the capacitors wouldn't see a voltage over their rating. In my experience, there will be those who would read this and think they could wire lower voltage capacitors in parallel and they would be safe too hook up to a higher voltage source. However wiring the in series  can allow them to be used with a higher voltage source, but the total capacitance will be reduced.  Knowing how capacitors wired in parallel or series behave allows you make use of what you have in the junk box or otherwise can attain readily to come up with what you need.  For more details read .  Given the low current provided by the suggested salvage solar cells, I'd suggest doing the initial charge of a high capacitance bank from other power source. After that initial charge the solar cells should able to restore the charge in  available time of sunshine.
static2 years ago
Good instructable, but for my kit I have a AM/FM pocket radio that I bought from Radio shack for not much more than the cost here. Use 2 AA batteries, while I hive never tried rechargeable batteries I assume so the solar power should work.  At lower volume levels Alkaline batteries last well, so I'd take extra batteries. My guess is the  plastic radio case doesn't weigh much more than the tin is is more durable. Everyone seems to ignore AM, when AM will be received almost anywhere. Good tools for making holes in light weight metal are a hand metal punch http:// and a tapered reamer .  Links used for illustration purposes so shop around. The punches may cost less  from vendors serving those in the auto DIY crowd looking for bargains.
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