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Author Topic: Specific Kit Construction Question, .0042uF Timing Capacitor?  (Read 774 times)

Offline LilFlowerBoi1303

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I have a more specific questions about a kit component. Do you think a .0047uF timing capacitor C1 would work properly instead of a .0042uF timing capacitor C1? Would it only slightly effect the resolution of pulses out of the 555? I do not want to damage the kit but also am having a difficult time finding a .0042uf capacitor.


Best and thank you kind sir

Offline sam

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Re: Specific Kit Construction Question, .0042uF Timing Capacitor?
« Reply #1 on: April 20, 2017, 10:43:19 PM »
Yes anything in the picofaraday range will give a sufficiently high 'maximum' pulse rate on the 555 to work with plants.  A higher value for the timing capacitor works better for humans, tho the sprout capacitor values and the threshold allows personal and inter-personal experiments.

In practice you can get away with a very wide range for the timing capacitor, especially considering that we are using the plant as an electrode and our 'resistance' can be ohms to megaohms.  The voltage divider which is made between the 'trodes' and the 100K resistor pulled up on Discharge Pin 7, create the primary measurement.  Changing the 100k will also allow different configurations and sensitivity.

One key is the 555 timer, by using a low voltage low impedance LMC555 we get additional sensitivity and compatibility with different microcontrollers (like 3.3v adafruit circuit playground)

You really can beat up a 555 without damaging it (1.5v-15v) plug anything into anything else or even into another 555 .... unlike an ATMega which can toast in microseconds if voltage is applied incorrectly.  I've seen 555 timers operate (strangely) even with reversed voltage, its as if they love that kind of crazy sh-t.

I always suggest to experiment, instead of getting one value of cap, look for an amazon/aliexpress/ebay box of various capacitors and see how they react with plants and stimuli.

cheers

Offline LilFlowerBoi1303

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Re: Specific Kit Construction Question, .0042uF Timing Capacitor?
« Reply #2 on: April 24, 2017, 12:30:29 AM »
Hey Sam thank you, I appreciate the support along this kit buildin journey!