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New JingleBot

New JingleBot

MillerSE FreeForm Layout

Miller Type 1 SE FreeForm Layout from Solarbotics.net

Circuit used: Miller Type1 SE from Solarbotics.net . Andrew Miller originally designed it in 1995.

Behavior of Circuit: From Solarbotics.net:
"As the solar cell charges the (4700 uF) storage capacitor, the voltage across the capacitor increases with time. Eventually it reaches the 1381's trip point, and the 1381 applies voltage to the base of the 2N3904. Since this is an NPN transistor, it "trips" and applies current to the motor. This state of affairs will continue until the 1381 sees a voltage that looks like its trip point less 0.3 V, at which point the 2N3904 goes "quiescent," and the solar cell resumes charging the storage capacitor. By choosing values for C1 and R1, we can "tweak" the performance of this circuit. If the load is (as shown above) a motor, we'll want R1 to be zero (i.e., no resistor), and C1 to be about 0.47 uF. Larger values for C1 result in longer (but less-frequent) "bursts" of motor activity; smaller values result in shorter (but more-frequent) activity. Larger values of R1 reduce the power going through the motor, as well as lengthening the "bursts" of motor activity. If the load is an LED or something similar, you'll need less power to drive it, and probably then want a non-zero value for R1."

Construction Notes: Parts include: 3300uF capacitor, 3.5v Solar cell, .47uF Capacitor, 1N418 Diode (click link for datasheet), 2N3904 Transistor, and a 1381G (2.4v). I used the freeform layout. As a rule of thumb, I try to use a 1381 variety that is 1v less than the voltage of the solar cell. I did not use R1 and just shorted the two pins together.December 2, 2008: I actually rebuilt the circuit twice...Be sure to check EACH solder joint as you make them. Life will be a lot simpler. The largest part of this build was the design of the topper, which I have modified twice already. I will need to use a wider base (the current base is from a hard drive) as the topper is a bit off center (deliberately, to help it jingle). I also may add another bell or two as well. But, the ‘bot functions as it should, even in low light.

Base for the New JingleBot

Base for the New JingleBot

Miller SE attached to motor

Miller SE attached to motor

 

Motor with base

Motor with Base

Part of topper

Part of Topper to the JingleBot

Part of topper

Part of Topper to the JingleBot

Another Angle of the topper

Another Angle of the Topper

December 3, 2008: I ended up scrapping the original topper design. I could not keep the jinglebot upright. So, I went with a wider spinning wheel and put two bells on brass wire. It uses 3 inches of brass wire, afixed to a bell, bent in the middle (see pictures below). It does not have to be exact. In fact, I prefer one taller than the other. I used hot melt glue to attach the wires to the spinning disk. I also used a small dab of hot melt glue to drive shaft of the motor to the spinning disk. It has a pleasant, random ring. Mission complete.

One set of bells

One set of bells

 

New bells installed

New bells installed

Top view of new bells

Top view of new bells

Closeup of attached bells

Close up of attached bells

 

Closeup of attached bells

Close up of attached bells

Finished bot

Finished bot

 

 

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