Wolf,
Things to check Holding current of Thyristor and saturation voltage typically 1.2 -1.4V.
So Vsupply - Vf Led - Vsat 1.4 then calculate the R value i.e. 6 - 3 - 1.4= 1.6/0.02 = 80R
If holding current is 20mA of less.
This does not allow for the Vsat of your PNP i.e. 0.6V and with a darlington this could be 1.4V so very quickly we are running out of voltage headroom.

Best Col

For the PNP use a logic level PMOS

 

Anyway..... even though the SCR test latch went fine, when I tried to repeat this process on the other side of my board (after current was powering the AMV and going through the 4017) the LED did stay lit, but just barely..... very dim flickering light. Same result with 150ohm or 1k at the anode of the LED, while 1k and 10k at the SCR gate.

I can hardly read the values of C1 and C2 of the astable oscillator. If the value is 0.1uF (104), then the frequency is about 79 Hz and it would be too fast for your clock to step the 4017. May be that's why your LED are dimly lite and flickering.

See the calculations here:

http://www.electronics-tutorials.ws/waveforms/astable.html

Allen

 

heres 2 slightly different transistor versions of your latch output-also the 4017 needs a reset signal on pin 15 so the counter is reset on switch on,your 2 transistor osc clocking the 4017 is ok but ditch the leds and add a third npn transistor to clock your chip and alter your timing components to slow the flash rate a bit.....if needed there may be more to come redesign wise if needed....your choice of power supply does not leave much headroom current handling wise tho

 

Hey MrChips....

I tried looking up info on that 74HC164 chip you mentioned earlier, but everything I've found on it seems to be associated with Arduino, which as I understand it is a hardware/software system for programmable IC's.

Can they be used without Arduino?

 

Here is the datasheet for 74HC164 and 74HCT164:

http://www.nxp.com/documents/data_sheet/74HC_HCT164.pdf

 

Ahhh.... yes...... I've seen this datasheet recently.... I understand maybe 1% of this data, and the word latch appears 0% in the document.....

Do you know of an example out there where someone built what I desire using this device w/o including programming?

Thanks

 

The 74164 is an 8-bit serial-in shift register.

Connect the two inputs (pins 1 and 2) to logic high.

When a clock signal is applied to the clock input (pin-8) a logic high will be shifted into the shift register and appear on the parallel outputs.

If you take the output of the last bit (pin-13), invert it and feed it back into one of the serial inputs it will result in a pattern that you may find useful for your application.

No latching is required. No SCR or PNP transistor required. Problem solved!

 

Heres a circuit using a similar device,can be built quite small so should be able to fit it in the space you have available...you can alter the timing components for the clock osc to suit...

 

Cool...... can you draw me a picture of that?

If you were building what I described, what is the most efficient way to get it done?

Can I fit all the parts onto a 1.7 x 2.3 PCB.... or less?

Thank You

 

Hi Sheldons..... thanks for posting again on this......

I don't recognize some of the symbols in that schematic you attached..... is the 47K resistor with and arrow going thru it a variable resistor?

I'm guessing that the 4 "flying bomb" symbols at the left side are all 4093IC's? I don't have any of those...

 

yes it is a variable resistor,the other symbols are the 4093 which is drawn that way as there is 4 independent 2 ip nand gates inside one 14 pin chip....

 

Wolf,
Things to check Holding current of Thyristor and saturation voltage typically 1.2 -1.4V.
So Vsupply - Vf Led - Vsat 1.4 then calculate the R value i.e. 6 - 3 - 1.4= 1.6/0.02 = 80R
If holding current is 20mA of less.
This does not allow for the Vsat of your PNP i.e. 0.6V and with a darlington this could be 1.4V so very quickly we are running out of voltage headroom.

Best Col

For the PNP use a logic level PMOS

Does this calculation need to be applied at every instance of a switching device in the circuit including the 2 NPN of the AMV?

If so, I'd have to agree with those who have already warned me that 6V will not be adequate to power this project.

Also, I'm seeing it in real time because as I add the LED/SCR/Resistor series one at a time to the 4017 pin-outs they only latch and remain so until I add the 4th set. Then the behavior becomes erratic and non repeating.

I'm still having some fun playing with this, but eventually I'll probably need to try different components as MrChips or Sheldons have suggested.

 

I can hardly read the values of C1 and C2 of the astable oscillator. If the value is 0.1uF (104), then the frequency is about 79 Hz and it would be too fast for your clock to step the 4017. May be that's why your LED are dimly lite and flickering.

See the calculations here:

http://www.electronics-tutorials.ws/waveforms/astable.html

Allen

At the moment I'm using 4.7uF for C1 and C2. R3 and R4 are 91K which should be about 1.5kHz. I don't know how to translate Hz to an actual clock speed, but the pin-out cycle from the 4017 is between 4 and 5 seconds.

When I replaced the 150ohm at R1 and R2 with 10K then the LED's on the AMV went barely visible, but the LED's on the chaser became nicely lit.

I should probably take a long break from this and read all the tutorials to cover the math I'm obviously not paying attention to, but who likes to read the instructions? LOL

 

Did you try MrChips' circuit using 74HC164? I simulated the circuit using proteus and it worked fine. See the sim attached.

But you cannot connect 6V directly to the 74HC164. You can pass the 6V through a diode (1N4001) to drop 0.6V before feeding the Vcc of the 74HC164.

Since you're also using the proteus sim, you might try it out yourself.

Allen

 

No Allen, it was on my list of things to do but I had not experimented with MrChips suggestion. Thanks for posting that schematic however, it sure looks clean compared to the mess I have here!

I finally gave up on the 6V supply and went to 9V..... things quickly improved 1000%. My circuit is running perfectly now (to my eyes).

Then I updated my Proteus schematic to reflect the exact components I'm using and it won't even start.... LOL. Nothing oscillates..... nothing lights. Oh well... at least I have one version that functions in the real world.

Not sure yet if I'll be able to stuff all this (about 50 components) into my little model let alone the 9V battery, so where's a quick place to shop for the chips and diodes I need?

 

Your original circuit would actually work in proteus if you change the power supply to 10V with clock pulses from the pulse generator of the proteus.

The clock circuit from your 2-transistors AMV would not work in proteus. I have tried this many times but I dont know the reason why... May be it was due to both transistors conduct or cutoff at the same time. But the circuit does work in real life.

Allen

 

Hey Allen..... I've seen quite a few instances now where things worked in the real world but not in the Proteus Demo software, and vice-verse. I'm very new to this whole study including the software end of it so I figured I had something configured wrong? Glad to hear I'm not an isolated case! LOL

Attaching the last schematic I actually used on the board, a pic of the boards, and a link to a short video of the effect I got.

http://www.youtube.com/watch?v=o3yrkszC748&feature=youtu.be

 

Although I might not use this actual design on my current model kit, I've decided (for many reasons) to go ahead and try to turn it into a PCB. Never having done this b4, any advice on do's and don't's is welcomed.

I started trying to layout the board with Proteus, but that wasn't helping me.... I wanted to see a real representation of the parts I would be dealing with. So then I drew scale pieces in a CAD program and played with them till I got something I liked. (photo attached).

All 52 components just squeezed onto a 2x2.75 board. It looks like I can put all of them on one side, and do all the connections on the opp. side.

Should I start pushing all the parts in place, wrap pins and snip ends in prep. for solder, and then use wire to jump the longer reaches? Is this the standard method of a "home brew" PCB?

Also, should I be gluing things down to assist the process? Is there a spray or dip that should be applied b4, during, or after?

Thanks,
Wolf

 

I must say it was very well laid out for a first timer. I have the same PCB that you have from eBay. It has 20 x 14 holes and it was not the largest one. For the IC you dont need to glue to the pcb. Just solder 2 corner pins of the chip and it will hold. If possible put an IC socket for the 4017 just in case.....

For the resistors, capacitors, transistors and LEDs, just bend the pins before cutting and they should hold. Good luck with you PCB construction and when you have finished, take a photo and share with us.

Allen

 

Thanks for the praise Allen..... I'll take all the confidence boosters I can get!

Minor Q regarding that last diagram I posted.... I keep looking at the lower left corner where the AMV parts are and wondering if I have those diagonal connections correct. Should they be coming off the capacitor pins or the resistor pins to connect to the transistor base(s), or do you think it matters?