Bike turning signals

[audioguru]

another thing...is the theory of operation of this circuit the same as its application?

The theory is simple:
1) The output of the 555 goes high and slowly charges the output capacitor through its output resistor.
2) The transistors have their inputs connected in series so when the rising capacitor voltage reaches +0.7V then the first transistor turns on. When the voltage reaches +1.4V then the second transistor turns on.
3) What happens when the voltage reaches +2.1V?
4) When the 555 times out and its output goes low then the diode at its output quickly discharges the output capacitor which turns off the transistors so they are ready to begin again.

 

[kinarfi]

Took the circuit and played with it, came up with this https://youtu.be/DF7cxT_JSWQ only I built it with a programmable unijuction transistor for the ramping voltage and used a jfet to feed the capacitor, always like charging caps with jfets because they give you a straight line ramp. On the video, poorly done, the first variations was adjusting the jfet current, then I was adjusting the pot that is hooked to the UJT gate, also added a couple of diode in series with the one that was already there to make the first LED turn of a little longer. This set up seems to give you a lot of adjustability from speed of flash to how long they are on before they recycle. Had to cover the lights with a bag to keep from blinding the camera.
On the drawings, it shows 1uf caps & 500K pot, but when built, I used 10uf & 50K pot because the circuit needed more current, but spice kept giving my small time errors with 10uf.
Thanks Colin55
Kinarfi

 

[kinarfi]

awilliams3537m, here you go

 

[colin55]

What's the point of putting the FETs in the collectors of the transistors. They are not doing anythiing.

 

[kinarfi]

on the normal circuit the voltage available to the LED gets less and less as you reach the last LED, so if you're using the same resistor on each LED, the current gets less.
The JFET and resistor set up creates a constant current so each LED get equal current regardless of voltage, (with in reason).
Kinarfi
That particular arrangement has always been a favorite of mine for constant current needs and when charging a cap with this set up, you get a straight line charge up instead of the usual 63.2% time constant curve.
Kinarfi

 

[kinarfi]

Colin, Try this little circuit out and change the Pot setting and watch the current through R1
Notice that current increases as voltage increases up to a point and then stays there and as you change the pot set, the level current changes too.
Enjoy

 

[colin55]

Simply use a resistor to supply 20mA.

 

[kinarfi]

Here's another file to look at, look at the voltage and current of each capacitor.

 

[awilliams3537m]

Kinarfi,

When i'm trying to view your .asc files, they show up in text only? Am i doing something wrong with them?