I’ve really enjoyed using the LM386 audio amp I built in Hack #5. I’ve used it to demo other audio creations as well and this week I’m using it again in a guitar tremolo effects box.
At the heart of this circuit is an RC filter that acts like a tone control on an audio device. It’s a low pass filter comprised of a .047 uF tantalum capacitor and a photoresistor also known as a photo cell or a LDR (light dependent resistor). The LDR’s resistance is modulated by light from a flashing LED which is controlled by the output from a 555 timer circuit in astable mode. As the resistance in the LDR changes with light intensity it alters the tone of the audio signal and creates a phaser like tremolo effect. The 555 astable circuit has a potentiometer that allows the blink speed of the LED to be speed up or slowed down and the LM386 amp is there to help boost the signal strength as the tremolo effect attenuates it somewhat. There are two other potentiometers on board. One that controls how much of the signal passes through the tremolo circuit and one to control the volume.
This is not only an effect box, it’s also a signal booster and it will brighten up the signal from any passive guitar pickup or microphone. It’s a fairly easy build that should be under $30 in parts. Below you’ll find a parts list, a schematic and a video of the entire build with a demo and explanation of the circuit. Have fun and as always….
Keep on hackin!
1 – LM386 audio amp
1 – 555 timer
1 – BC547 NPN transistor
1 – LDR (photoresistor)
1 – Bright white LED
1 – 1000 uF Electrolytic capacitor
1 – 220 uF Electrolytic capacitor
1 – 100 uF Electrolytic capacitor
1 – 10 uF Electrolytic capacitor
1 – .01 uF Ceramic capacitor
1 – .047 uF Ceramic capacitor
1 – .047 uF Tantalum capacitor
2 – 1K ohm resistor 1/4 watt
1 – 100 ohm resistor 1/4 watt
1 – 470 ohm resistor 1/4 watt
1 – 10 ohm resistor 1/4 watt
1 – SPST power switch
2 – 1/4″ phono jacks
2 – 10K ohm potentiometers
1 – 5K ohm potentiometer
1 – 9 volt battery clip
1 – 9 volt battery
1 – 5mm power jack
1 – Perfboard or make your own PCB.
1 – Plastic or metal enclosure
Some 22-24 ga. hookup wire
Shrink wrap to couple the LED to the LDR
OPTIONAL: One more LED of the same type to mount on the outside of the enclosure as an indicator of power on and tremolo speed.
Wire it in parallel with the other LED with it’s own 470 ohm resistor.
I love the sound of tube amps! Warm tones that can only come from an analog device.
On a recent trip to my landfill, I found this old Webcor turntable in the unwanted electronics pile. Now, even though I wasn’t supposed to take things from this pile I grabbed it up and put it in my car. When I got it home I opened it up and was quite surprised to see that it was in wonderful condition and the amp still worked! The turntable section had a few issues though. The speed was off and the cartridge was junk. Rather than try to restore it I decided it was a good candidate for a hack! I made a decision to turn it into a small practice amp for guitar or bass or vocals! It ended up sounding really nice as you can hear in the track I recorded at the intro to the video.
One of the really cool things about the electronics of the 40’s to the 70’s was the inclusion of a schematic inside the unit somewhere. This was a very handy circuit reference for the repair tech to use when something needed fixing. Yes, people actually used to fix things rather than throwing them out and rushing out to buy another one like we do these days.
Enjoy the photos and video and til next time, keep on hackin!
When I started Hack A Week I said I’d be doing all kinds of projects including food! Well with all these eggs I have from my chickens I thought a food hack about eggs would be in order.
Eggs are just awesome. They’re a good source of protein and they taste great! I like eggs any way ya cook em but my favorite is Eggs Benedict.
In this weeks video I’ll show you how to cook eggs with your espresso machine, how to separate egg yolks from the whites,. how to poach and egg and how to make Hollandaise sauce for Eggs Benedict!
If you find yourself feeling hungry after the video, go make some eggs!
I promise that I’ll be getting back to some electronics next week, so until then…
Back in hack #4, I built a chicken tractor for some chickens I had purchased. Well what started out as six chickens has since been reduced to three. One got eaten by a Fox and two fell victim to one of my dogs. The dogs have since learned to co-habitate with the chickens and they’re getting along fine now. The chickens are laying fresh eggs on a daily basis which I really enjoy eating and sharing with friends.
They’re full grown chickens now and they really needed a new shelter for the coming winter month so for this week’s project I built them a new bigger chicken coop!
In this video I go through all the steps it took to build a 4′ x 4′ chicken coop with three nesting chambers. It has a door on the back which makes it very easy to gather the eggs daily.
All the animals make an appearance in this video so enjoy, and keep on hackin!