Help 4-39 Make Electronics

101

01:38:35

Does anyone know why this isn't working?

This is from the Make Electronics book, second edition, page 164, figure 4-39.  I have this working in real life, and I just did it in iCircuit and it worked the first time.  I have spent a lot of time in EveryCircuit and I can't get it to work.

Long story short, the wire between the 68uF capacitor and pin 2 should start at 9V, and then descend so that it flips the trigger when it gets down to 3V.  

But here, that wire goes to 9V when I close the switch, and then it stays there forever.

What am I missing?

published 5 years ago

wyoelk

5 years ago

It's hard to say without knowing if this an Astable, Monostable or Bistable 555 mode circuit. Are one of these what you are trying to make? _ _ http://everycircuit.com/circuit/5848281658425344 or http://everycircuit.com/circuit/6453605530599424

Robert_Kidd

5 years ago

Your LED will never light with a 470k in series with it. Might be worth checking all values and connections against original. What do you want this circuit to do?

silveryguy10

5 years ago

I figured it out. The circuit was fine, it's just that the graphing time was wrong. (and yes, the resistor was wrong, but that wasn't my concern.) This is a countdown timer. Once you turn the 9V power on, there is a 60 second delay until the 555 output turns on. I had the graph set to the default 5ms (or whatever). I had to change it to something like 1 second, or the maximum of 5 seconds so that I could actually see that change in voltage over the 1 minute span. Is there any documentation on EveryCircuit? I can't find any. That graph was one of the things that I was wondering about even before this happens. And who knows what else I am missing, or what other useful tips I could learn from the documentation.

Robert_Kidd

5 years ago

There is no documentation. I’ve heard they think it’s so intuitive none is needed! Clearly not the case.

Robert_Kidd

5 years ago

Put “EC Teach” in search field and you will find some tips. I started this a while ago intending it might be useful but not many people have come forward with input sadly.

lmccoig

5 years ago

Add ground to battery negative. Connect 555 pins 4 and 8. Adjust other values.

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