Night rider scanner

[mixos1]

This redrawn simplfied circiut from my collection was drawn ina special way by circiut maker and retraced in black to highlight it enougth to come out when photographed, for posting, ill post another similiar one soon and because it uses more of the 4017 decade counter pins, it allso makes a good decade counter testor.

by Steven (received via e-mail)

View attachment 35301

 

[audioguru2]

Mixos,
Steven's circuit is not a knightrider, it is a chaser that misses a few steps. We have discussed knightriders and chasers recently in this site at: Electronic Projects Design/Ideas, "LED Flasher (very interesting)".
In Steven's circuit, R5, the LED current limiting resistor, is not needed because the 4017 outputs have built-in current limiting at about 9mA with an 8.3V supply.
In Steven's circuit, the transistors in the multivibrator have their base-emitter junction driven beyond their 7V maximum rating which causes damage to them.
A good knightrider project is in our site's project section here:
http://www.electronics-lab.com/projects/motor_light/035/index.html

 

[MP1]

steven, since you have already built this circuit, could you please reply to the questions asked?

MP

 

[audioguru2]

In order to avoid continuing confusion about knightrider/chaser, for those who have not seen the American TV show, is it possible to include the animated GIF:

into the project article, above?

Is it also possible to remove the phrase,"Knightrider" from the Projects Index for the chaser circuit:
http://www.electronics-lab.com/projects/motor_light/028/index.html

 

[steven2]

with so many circiuts in my collection i havent got to biuld this night rider scanner as it was a talking electronics circiut from my colection but i now favour the one in this site, from steven

 

[audioguru2]

MP,
Thanks for fixing the Projects Index.
Isn't it possible to include the animated GIF into the "Knightrider LEDs for Model Cars" project? I have a solution for anyone who complains that the GIF shows 10 LEDs but the project has only 6.

 

[steven2]

from steven, oh ill see if i still have the talking electronics mag and email the pic of the night rider scanner by talking electronics, yes it is a kit for the car. did i make any boo boo

 

[Nettron]

Heres a schematic of my up-down sequencial LED flasher that can sequence 16 LEDs, not sure how many LEDs were used in the original knightrider car .

http://onfinite.three10.com/libraries/display.php?lid=8114&d=c524448053f994bcb48126b1b3904945

 

[audioguru2]

Nettron,
Nice circuit. But 5 chips (the 5th is a 5V regulator) just to flash leds?
The original knightrider car probably used light-bulbs. I would guess 8 to 10 of them.

 

[MP1]

Nettron, thanks for sharing.

Do you have a picture of the prototype? I think others would be intrerested to see it as well if you do.

MP

 

[Nettron]

But 5 chips (the 5th is a 5V regulator) just to flash leds?

Audioguru, you have a point there, i was thinking the same thing when i was first designing the thing. Wish the 74154 had had some type of F-F and up/dn counter built-in. I had thought about using a 4017 but it would only give me sequencing in one direction with 10 LEDs. Do you know of a stand alone IC that can do dual sequencing of 16 LEDs or more ?

Do you have a picture of the prototype?

Sorry MP, no i dont. I gave the board to my bro, seams he used it in a holloween costume for light effects. But I have the ExpressPC board layout on a floppy somewhere, i'll post it here if and when i find it.

 

[audioguru2]

Nettron,
We have a 6-LED knightrider circuit in our projects section. The 4017 counts forward lighting LEDs 0-5, and diode gates are used to light those LEDs in reverse order while the 4017 continues its count of 6-9. From a 9V battery, the 4017's outputs are current-limited to about 11mA, so a current-limiting resistor is not needed. The project is here:
http://www.electronics-lab.com/projects/motor_light/035/index.html

An LM3914 dot/bar-graph chip lights 10 LEDs sequentially in both directions when fed with a dual-opamp triangle-wave generator. The LM3914 can be cascaded to allow umpteen-dozen LEDs, but the set-up adjustment will be tricky after maybe 50 LEDs.
A D-A converter would feed cascaded LM3914s beautifully.

 

[Nettron]

We have a 6-LED knightrider circuit in our projects section.

Yes i was looking at that earlier, nice little compact design. Its also available from Doctronics in kit form here:

http://www.doctronics.co.uk/kits.htm#chaser

Unfortunately wasnt enough LEDs for my app.

An LM3914 dot/bar-graph chip lights 10 LEDs sequentially in both directions when fed with a dual-opamp triangle-wave generator.

Yep had looked into that as well, was thinking about taking the ramping voltage right off the timing capacitor on a 555 astable and use the LM3914 in dot mode. only problem was i didnt have a 3914 handy so tried the nuts-n-bolts route using comparators (LM339), had lots of those. But the design became too complex and just plain overkill, so later dropped the idea (violated the KISS rule). But something worth looking into.

 

[audioguru2]

Nettron,
Don't use the ramping voltage of a 555's timing capacitor to drive an LM3914 because it is not linear with time. It would start counting the LEDs quickly, then slow down when nearing each end. The integrator output of a dual-opamp triangle-wave generator is perfectly linear.

 

[audioguru2]

Nettron,
Have you considered distorting the ramp so the LEDs slow down at each end like a pendulum?

 

[Nettron]

Don't use the ramping voltage of a 555's timing capacitor to drive an LM3914 because it is not linear with time.

Remember i didnt have a LM3914 and was using LM339 comparator IC's. The idea i had in mind to solve the non-linearity problem, without adding another IC , was two-fold: 1. use different amounts of feedback around each comparators to "pull" the input voltage over threshold at appropriate timing intervals, 2. use a different reference voltage for each comparator. Yeah i know, it sounds ugly but that was 2 years ago and i havent looked at it since.

Have you considered distorting the ramp so the LEDs slow down at each end like a pendulum?

Hmm...interesting,hadnt thought of that. AG maybe you should post a design based on that idea,I for one would really like to see something original.

 

[MP1]

yes, audioguru, could you post an original design for others to view?

MP

 

[audioguru2]

The exponential charge/discharge of a 555's timing capacitor IS like a pendulum! But the effect is reduced by the 555's lack of full charge and discharge (1/3 of +V to 2/3 of +V).
So maybe it would be best to low-pass filter a square-wave in order to obtain an alternating voltage that changes very quickly at the beginning and very slow at the end.
What do you think about that?
How many LEDs?

 

[Nettron]

Appearently not all that original .

http://www.eki.com/product.asp?number=2009

Maybe add a few more rows of LEDs, with different numbers of LEDs in each row, to simulate the "string" with the longest row representing the bobbin at the end. Maybe this belongs in another thread ?

So maybe it would be best to low-pass filter a square-wave in order to obtain an alternating voltage that changes very quickly at the beginning and very slow at the end.

Appears do-able. Another option could be to build a circuit based on the internal window comparator on the 555 timer IC but with independent control over the charge/discharge rate and window reference voltages ( Vtrip upper/Vtrip lower).