Wow these are small, Photo Light Sensitive Photoresistor

[audioguru]

Current in the LEDs is very low so they are not as bright as they could be.
Did you notice that the two LEDs do not actually blink? Instead they alternate with one LED on then the other LED is on so one LED is on continuously.
My Chaser circuit causes each LED to blink for a duration of 30ms (long enough for out vision to see the full brightness) then each LED is very bright but the two AA cells last for months, blinking day and night. Yours with the light detector might last for one year if they are modified to blink like that.

 

[gary350]

Current in the LEDs is very low so they are not as bright as they could be.
Did you notice that the two LEDs do not actually blink? Instead they alternate with one LED on then the other LED is on so one LED is on continuously.
My Chaser circuit causes each LED to blink for a duration of 30ms (long enough for out vision to see the full brightness) then each LED is very bright but the two AA cells last for months, blinking day and night. Yours with the light detector might last for one year if they are modified to blink like that.

I want to see your chaser circuit. I know what your saying about the circuit I built it is like having a SPDT switching 2 lights on/off over & over from a distance it appears to be 1 light ON all the time if the lights are close together.

 

[audioguru]

I have 6V chasers that use 3.5V blue and bright green LEDs but here is my 3V chaser that uses 2V red LEDs:

 

[gary350]

I have 6V chasers that use 3.5V blue and bright green LEDs but here is my 3V chaser that uses 2V red LEDs:
[/QUOTE

I thought you were talking about a circuit with 1 or 2 LEDs.

 

[audioguru]

You wanted to see my chaser so I posted it.
It uses a 74HC4017 IC to turn on 10 LEDs one after the other as a chaser. The IC never turns off LEDs at any time, one of the 10 LEDs is always turned on like in your flip flop multivibrator circuit, then its battery would be dead in one week. So I used some of the Schmitt Trigger inverters in the 74HC14 IC to blink each LED for only 30mS which is long enough for our vision to see the full brightness but is short enough to use only a tiny amount of the battery power, because each LED is turned off for most of the time.

The circuit also saves power by chasing around and around a few times then a pause without any light before chasing around and around again.

 

[gary350]

audioguru Which part of the chaser circuit is the Schmitt Trigger? Maybe I can use that to limit flash time to save the battery in my circuit. Your IC circuit gave it an idea, why did I not use a 555 to flash 1 LED at about 1.5 seconds flash rate. Does a 555 use lots more power than the circuit I have?

 

[gary350]

Meter reads battery amps to be 1.16ma in the dark for the LDR & LED circuit and .265ma is the sun. With LEDs off I assume Q1 is using power. Average assuming sun light conditions are 12 hrs ON and 12 hrs OFF = average is .7125 ma. Maybe Q1 resistor can be increases to lower battery drain and still find a sweet spot with good LED flashing. I will experiment with that.

My original flasher circuit meter reading jumps up & down from 1.49ma to 2.51ma. I added a large capacitor across the power supply to see if that smooths meter ready out but it does not. Looking at meter & LEDs blink at the same time it appears every time a capacitor is charging meter reading is high & after capacitor is charged meter reading is low. Average = 2ma.

Old flasher circuit uses 2ma 24 hrs per day.
New LDR & LED circuit uses an average of .7125ma 24 hrs per day.
That is a 2.807 times increase in battery life.
2 D batteries last 4 months now they will last 2.8 x 4 = 11.2 months

Double check my math someone did I make a mistake 11 months seems too good to be true? This could be true or better considering days are short at the moment 6 months from now days will be 15 hours long LDR circuit will be off an additional 6 hrs per day in summer.

The first picture is the original LED flasher circuit.
2nd picture is first circuit with LDR circuit added.
3rd picture is RED color LED flashing
4th picture is YELLOW color LED flashing.

It is not easy taking a picture when LED is ON I took 34 pictures trying to catch them both ON. When an LED goes off light slowly goes out.

 

[shortbus=]

Which part of the chaser circuit is the Schmitt Trigger?

Do you know what a Schmitt trigger symbol looks like? That will tell you what they are in the schematic.

 

[HappyDoggy]

第一张图片是原始的LED闪光灯电路。
2nd picture is first circuit with LDR circuit added.
3rd picture is RED color LED flashing
4th picture is YELLOW color LED flashing.

It's amazing! Where will they eventually be applied?

 

[gary350]

It's amazing! Where will they eventually be applied?

I have 18 of these all around the house & yard. It is a fake security system to fool thieves and keep them away. So far so good several houses all around us have been broken into but not us.

 

[gary350]

Do you know what a Schmitt trigger symbol looks like? That will tell you what they are in the schematic.

Google search shows Schmitt trigger symbol as a triangle with symbol in center but I still don't know what Schmitt trigger is? Is that something a person buys then you just solder it into the circuit?

 

[audioguru]

You mentioned using a 555 but maybe you have not seen the datasheet of the old original high current 555. Its minimum supply voltage is 4.5V and it draws a current of up to 6mA even when it has no load. The newer Cmos LMC555, TLC555 and ICM7555 have a minimum supply of 2V and draw no current when there is no load.

The modern 74HCxxx logic ICs also have a minimum supply of 2V and use no current when there is no load.

A Schmitt Trigger output has a "snap action" when its input voltage reaches a certain voltage. A triangle is an opamp or a Logic inverter. A Schmitt Trigger can be designed into a circuit with resistors and/or capacitors.

 

[gary350]

You mentioned using a 555 but maybe you have not seen the datasheet of the old original high current 555. Its minimum supply voltage is 4.5V and it draws a current of up to 6mA even when it has no load. The newer Cmos LMC555, TLC555 and ICM7555 have a minimum supply of 2V and draw no current when there is no load.

The modern 74HCxxx logic ICs also have a minimum supply of 2V and use no current when there is no load.

A Schmitt Trigger output has a "snap action" when its input voltage reaches a certain voltage. A triangle is an opamp or a Logic inverter. A Schmitt Trigger can be designed into a circuit with resistors and/or capacitors.

I knew there must be a reason I have forgotten why i am not using a 555.

It sounds like resistor & capacitor make a timer charging circuit through a Schmitt Trigger to flash 1 LED am I correct?

The old neon light flasher was a resistor & capacitor in series with PS and NE2 when capacitor charged to 55v the neon flashed and discharged the capacitor. Is Schmitt Trigger doing the same thing?

 

[Visitor]

LED Circuit Collection

 

[shortbus=]

Google search shows Schmitt trigger symbol as a triangle with symbol in center but I still don't know what Schmitt trigger is? Is that something a person buys then you just solder it into the circuit?

Do you even read what Audio and others tell you? He even gave you a part number to look up the data sheet with. He must realllly like you to put up with your nonsense.

 

[gary350]

Do you even read what Audio and others tell you? He even gave you a part number to look up the data sheet with. He must realllly like you to put up with your nonsense.

I see 2 IC part numbers 74HC4017 IC and 74HC14 IC but no Schmitt trigger part number. I read the information again 3 times I think that means there are Schmitt triggers inside of the 74HC14. After looking up 74HC14 I remember looking that up the other day but I did not know what I was looking at. Now I found a 74HC14 video and now I understand this is Schmitt trigger. 10uf capacitor makes Schmitt trigger run at 2 hz in the video.

74HC14 - - Video Search Results

The search engine that helps you find exactly what you're looking for. Find the most relevant information, video, images, and answers from all across the Web.

video.search.yahoo.com

 

[Mickster]

74HC14 is a hex Schmitt trigger inverter.
74HC04 is a hex inverter.

Dave has a video explaining Schmitt triggers :

 

[gary350]

Once I got on the right track I found videos and circuit drawings. 74HC14 is 6 square wave generators in 1 package.

Circuit drawing 470 ohm resistor limits current to LED. 10uf cap & 1K resistor sets the time. Change the values of R1 & C1 it changes the duty cycle. This circuit runs on 3v.

One interesting circuit used 1 new D battery to charge 2 caps in parallel with the 74HC14 then discharge the 2 caps in series to light up the LED. Video made special effort to mention D battery is brand new that makes me think circuit won't work when battery gets low. Video, breadboard, no circuit drawing.

I picked this circuit it has only 5 parts it will be quick & easy to build 18 of them after I build 1 and test it first.

 

[audioguru]

The Schmitt Trigger logic inverter makes a very simple oscillator with only one added resistor and one added capacitor. Other oscillators need more parts.
The Schmitt trigger "pulse duration reducer" makes the LED current pulses for a short duration so that the battery can last for a long time but the LED blinks are bright.

Gary, you found an old circuit with a good voltage doubler but it probably does not work since its 74HC14 IC needs a power supply that is at least 2V. The 1.5V battery in the circuit drops to 1V as it is used. This is the kind of modern circuit you should be making using two 1.5V battery cells to make 3V and the voltage doubling capacitors and resistors are not needed. I modified it to work from a 3V battery and added a few important things.
This circuit uses inverters that are difficult to turn off with a light detector circuit, therefore a 74HC132 quad NAND Schmitt Trigger logic gate IC should be used instead.

 

[audioguru]

Gary, your 74HC14 circuit has five of its Schmitt Trigger inverters without their inputs connected to anything, so those unused inverters are drawing a lot of battery current all the time. If you connect their inputs to 0V to disable them then they will draw no current.
The IC sets the duty cycle which might be changed with an added diode in series with an added resistor.

Your circuit uses a 1k resistor charging and discharging the 10uF capacitor with a fairly high current. That current comes from the battery. Use 10M and 1nF capacitor for it to do the same thing but without wasting battery power.

I think the 470 ohm resistor limits the LED current so low that it is dim. Use 82 to 100 ohms instead.

All electronic circuits should have a capacitor across the power supply connections.