Brain Cortex Part 3 - Solar Panel

This solar panel will keep the cortex brain alive

BRAIN CORTEX SOLAR PANEL

Polycrystalline panel back side

This post represents more updates to our Brain Cortex in a jar project. The rabbit jar, as discussed in the previous post, has slightly squared off sides and this is a perfect form factor for the internal solar panel that will be statically mounted inside along the jar.

Walk in electronics store - Taiwan

POSITIONING
In this way, the jar can be positioned sideways stationary to gather in light relative to the incoming light angle of the source to create the Propellers power, without the problems of a round jar rolling around or deflecting the incoming light at various circular induced angles.

Homes Kit Solar Panel (Taiwan)

FUNCTION
The panel is fully functional with room ambient light, artificial lighting, and direct solar light. During the day when located in a room, the cells act as a trickle charger for the two 1.5-volt rechargeable AA batteries at approximately 1.3 volts. With more direct lighting, the Propeller chip is sustainable at its full requirement of 3.1 volts without battery deficit depletion.

Solar Panel SM-8656, 3V @ 120 MA

NO BATTERY NEEDED
Under certain lighting conditions where the voltage output is around 3 volts, the solar panel can power the Cortex without battery power.

DAY NIGHT MODE
We are working on a circuit that will automatically switch the Cortex from day to night mode. In day mode, the solar panel provides power and recharge ability, and in night mode the Cortex switches over to battery power.

SOLAR PANEL SPECS
The Solar Panel is purchased from the main electronics parts store. The Homes polycrystalline solar module is rated for operations at 3v @ 120 mA, part number SM-8656,  88 (L) X 58 (W) X 5 (H) mm, weight 35.85 grams. Homes provides a choice of 30 different solar panels and solar modules. Most of these are in stock at the electronics parts store mounted near the ceiling.

EXPERIMENT
In a typical experiment, the panel put out 1.3 volts in ambient room light and up to 3.4 volts directly under a high intensity lamp.

COST & POWER
The NT$299 (US$10.17) priced Solar Panel has a rating of (P=EI) 25 ohms, 0.36 watt as calculated based on its specification rating. 

ONLINE POWER CALCULATOR
Here is an online calculator for calculating power and other values. http://www.sengpielaudio.com/calculator-ohm.htm.

MANUFACTURER
The manufactures web site is at http://www.100y.com.tw/htm1/542901234.htm. As mounted and protected in the jar, the estimated expected life of the solar panel is from 20 to 40 years.

Propeller Simple Spin Board Part 3

The main battery supply is switched off, however the LED blinker program continues to operated from USB power. The added breadboard circuit controls the brightness of the LED.

PROPELLER SIMPLE SPIN BOARD
Experiment 3 - Running on USB Trickle Power

Last time we disabled BOE (Brown Out Enable) so that our simple prop board could run on low power. We then asked the question, "How low can we go?" Exploring and experimenting led to a discovery.

First we ran the LED blinker program. Then we shut off the 3.0 volts battery power supply expecting the program to shut down and the LED to go off. However, in a darkened room, the LED was dimly continuing to blink, and the program stayed in memory continuing to run properly.

TEST PROGRAM
pub main
dira[15] :=1
repeat
 !outa[15]
  waitcnt(clkfreq*2 + cnt)

The program is modified to slow down the LED blinker so the meter can settle to get a good reading of voltage drop across the LED.

RESULTS
Run the program with the power supply connected. Remove the power supply. With the USB port connected, the prop chip has a 2.32 voltage high from P15 when the circuit's power supply is off and the USB cable remained connected.

Tests were performed on an iMac with an unpowered four port HUB. When the power supply is on, the prop chip has a 3.0 volt high from P15. The simple way to increase the LED brightness is to use a 5 volt LED or a high intensity LED, carefully controlled without the dropping resistor. When switching back to the full 3.0 volts power supply, the resistor must be reconnected beforehand.

A transistor circuit can also boost the power to the LED. The illustration shows an experiment. The shown circuit is found in Parallax' book, "What's a Microcontroller."

CAVEATS
When the main power is shut off, the program continues to run and the LED continues to blink. When the USB is disconnected, there is no power to the prop circuit and the program is lost. With USB power attached again, without the mains power supply, the prop is not detected and the program will not reload.

IDEAS
One idea is to place the amplifier circuit in between the battery power supply and the prop circuit to see if the programs will continue to load on USB power only. The most simple approach - substitute a 5V LED and the LED dropping resistor can be removed to increase the LED brightness. When switching back to the full 3.0 volts power supply, the resistor must first be reconnected. Or simply route the USB +5 Volt line to become the prop's power supply.

LINKS TO PROPELLER SIMPLE SPIN BOARD EXPERIMENTS

Experiment One - Bare Bones Circuit
http://humanoidolabs.blogspot.tw/2013/07/propeller-simplex-spinner.html
http://humanoidolabs.blogspot.tw/2013/07/bare-bones-propeller.html

Experiment Two - Disabling BOE for Low Power Operations
http://humanoidolabs.blogspot.tw/2013/07/propeller-simple-spin-board-part-2.html

Experiment Three - Running on USB trickle power
http://humanoidolabs.blogspot.tw/2013/07/propeller-simple-spin-board-part-3.html

Experiment Four & Five -  Improving Reliability
http://humanoidolabs.blogspot.tw/2013/07/propeller-simple-spin-board-part-5.html