Help with using a PIR to trigger a NE555

ericgibbs

Joined Jan 29, 2010
19,084
Hi,
I guess you know that the White Dir LEDs can only light when the 555 Output pin is High, after being Set by Sense #1, is that acceptable to the expected operation.?

Also please check my image clip in post #79, it looks incorrect.

E
 

Thread Starter

AllisonAmg

Joined May 18, 2020
71
Hi,
I guess you know that the White Dir LEDs can only light when the 555 Output pin is High, after being Set by Sense #1, is that acceptable to the expected operation.?

Also please check my image clip in post #79, it looks incorrect.

E
The White LED's can only be lit when the Green LED is also lit.

Allison
 

AnalogKid

Joined Aug 1, 2013
11,196
I guess you know that the White Dir LEDs can only light when the 555 Output pin is High, after being Set by Sense #1, is that acceptable to the expected operation.?
Truth Table
StageConditionREDGREENWHITE
ATrain Triggers Sensor 1 and the Timer is StartedYESNONO
BPre-Set Time Elapse (J1 = C2) or Train Triggers Sensor 2 (J1 = C1), Points Not-SwitchedNOYESNO
CPre-Set Time Elapse (J1 = C2) or Train Triggers Sensor 2 (J1 = C1), Points SwitchedNOYESYES

ak (62, 66, 68, 75, ...)
 

ericgibbs

Joined Jan 29, 2010
19,084
hi Analog,
I am interacting with the TS, if I have query that has arisen when reading the TS's previous posts, I will ask the TS to reply.

E
 

ericgibbs

Joined Jan 29, 2010
19,084
Hi Eric, I used the diagram
Hi A,
If you recall, I had to disconnect the Reset to the 555 from the Sense2 in order to run that simulation post #72 to show the White On period.

Recapping:
The Sense 1 output [Vset] is connected to R4/Trig and the Sense2 output [Vres] to 555 RST, the Manual reset push button will also goto pin4 RST.

Eric
 

Thread Starter

AllisonAmg

Joined May 18, 2020
71
Hi A,
If you recall, I had to disconnect the Reset to the 555 from the Sense2 in order to run that simulation post #72 to show the White On period.

Recapping:
The Sense 1 output [Vset] is connected to R4/Trig and the Sense2 output [Vres] to 555 RST, the Manual reset push button will also goto pin4 RST.

Eric
Hi,

Now i am now totally confused, i am at a point where i am about to give up and go bury my head in the sand !!!

I cant seem to get my head around this, looks like i will end up buying ready made signals.

Thank you all for the help you have given me, but i dont think i am grasping this at all.

kindest
Allison
 

ericgibbs

Joined Jan 29, 2010
19,084
hi Allison,
Don't give up.
If you really want to get a handle on the circuit I am willing to continue.

Which part of the project is causing you a problem.?

Eric
 

Thread Starter

AllisonAmg

Joined May 18, 2020
71
hi Allison,
Don't give up.
If you really want to get a handle on the circuit I am willing to continue.

Which part of the project is causing you a problem.?

Eric
Hi,
I do want to continue, but i seam to be going around in circles.

What i wanted i thought would be simple enough, but it doesnt seem so now.

Kindest
Allison
 

MisterBill2

Joined Jan 23, 2018
19,389
If a flip-flop function is what you seek then why not use na FF, such as the CD4013 or equal? And why confuse the responders by calling a reflective photoswitch a PIR (Passive Infr Red) device? They are very much different.
And now I se that this thread has been going around for a very long time.
 

MisterBill2

Joined Jan 23, 2018
19,389
Hi,
I do want to continue, but i seam to be going around in circles.

What i wanted i thought would be simple enough, but it doesnt seem so now.

Kindest
Allison
Evidently the desired function has not been presented in enough detail to allow a satisfactory answer. That happens frequently here. If this is a model train system then a reflection from the train is not the best choice, unless the sensor is looking up through the track. Using the same sensor shown in a much earlier post as a beam-break triggered sensor can provide a much more reliable operation. And an adequate description of the desired output power and function will allow a useful response.
 

AnalogKid

Joined Aug 1, 2013
11,196
Here is an updated schematic that includes the two manual switches.

Note that this circuit looks more complex than it really is. The four logic gates are all in one IC package, and two of them are unnecessary. With logic ICs (especially CMOS), unused inputs must be connected to either a logic 0 or logic 1 voltage to prevent them from "floating". U1C and U1D act as two inverters in series. They do nothing to the signal or for the circuit, but connecting them to something keeps them out of trouble.

If you really want to scrimp on parts, one IC can host two independent circuits. U1C and U1D could be configured as a flipflop (like U1A and U1B) for a separate channel. In that case, the right (+) end of C1 would connect directly to the Q1 gate. The green (and white) LED(s) would not snap on quite as crisply.

This circuit assumes that the two SENSE input pull up resistors are on the IR modules.

ak
Train-Lights-4-c.gif
 

MisterBill2

Joined Jan 23, 2018
19,389
Evidently the desired function has not been presented in enough detail to allow a satisfactory answer. That happens frequently here. If this is a model train system then a reflection from the train is not the best choice, unless the sensor is looking up through the track. Using the same sensor shown in a much earlier post as a beam-break triggered sensor can provide a much more reliable operation. And an adequate description of the desired output power and function will allow a useful response.
One more thing, which is that since the sensors have an IRLED, (emitter) they are not by any stretch PIR devices. They are reflective-mode switches, and will work best with some intentional reflector so that the passing model train will break the beam.At that point , if there is a rising voltage output, you can use that to trigger an actual flip-flop such as a CD4013, which will trigger on the rise of the voltage to the set terminal. The benefit is that it can be used for voltages between 4 volts and 15 volts, so it is simple to match the operation voltage to the IR switch output. And a time delayed output is very simple as well. Plus, you get two independent FF devices in one package.
 

AnalogKid

Joined Aug 1, 2013
11,196
The sensor is reflective, with an adjustable range of approx 2 - 30 cm. The output is open collector (LM393) with a pullup resistor to Vcc (3.3 to 5.0 V). The output goes low on sensing an object.

ak
 

Thread Starter

AllisonAmg

Joined May 18, 2020
71
Here is an updated schematic that includes the two manual switches.

Note that this circuit looks more complex than it really is. The four logic gates are all in one IC package, and two of them are unnecessary. With logic ICs (especially CMOS), unused inputs must be connected to either a logic 0 or logic 1 voltage to prevent them from "floating". U1C and U1D act as two inverters in series. They do nothing to the signal or for the circuit, but connecting them to something keeps them out of trouble.

If you really want to scrimp on parts, one IC can host two independent circuits. U1C and U1D could be configured as a flipflop (like U1A and U1B) for a separate channel. In that case, the right (+) end of C1 would connect directly to the Q1 gate. The green (and white) LED(s) would not snap on quite as crisply.

This circuit assumes that the two SENSE input pull up resistors are on the IR modules.

ak
View attachment 209110
Hi,

Thank you soo much

Allison
The sensor is reflective, with an adjustable range of approx 2 - 30 cm. The output is open collector (LM393) with a pullup resistor to Vcc (3.3 to 5.0 V). The output goes low on sensing an object.

ak
Hi,

Just done a BOM for that Circuit Diagram, and excluding Switches, Sensors, Board and consumables, it comes to around £2.10 each, which pleasently supprised me.

Thank you again

Kindest
Allison
 

Thread Starter

AllisonAmg

Joined May 18, 2020
71
Hi,

Thank you soo much

Allison


Hi,

Just done a BOM for that Circuit Diagram, and excluding Switches, Sensors, Board and consumables, it comes to around £2.10 each, which pleasently supprised me.

Thank you again

Kindest
Allison
I will build as per your diagram, i am not going to scrimp on IC's not worth the effort.

Allison
 

AnalogKid

Joined Aug 1, 2013
11,196
I'm working on a component layout wiring diagram. You said you would be building many of these boards. Is it your intent to have a 5 V regulator on each one, or have one separate (possibly purchased) 12 V to 5 V regulator module for the entire system?

ak
 

Thread Starter

AllisonAmg

Joined May 18, 2020
71
Hi,
I guess you know that the White Dir LEDs can only light when the 555 Output pin is High, after being Set by Sense #1, is that acceptable to the expected operation.?

Also please check my image clip in post #79, it looks incorrect.

E
Hi,

Each board will be self contained, except for the 12vDC, Sensors, Switches, and LEDS

kindest
Allison
I'm working on a component layout wiring diagram. You said you would be building many of these boards. Is it your intent to have a 5 V regulator on each one, or have one separate (possibly purchased) 12 V to 5 V regulator module for the entire system?

ak
Hi,

Each board will be self contained, except for the 12vDC, Sensors, Switches, and LEDS. I have no intention of running a 5v Bus around the layout, I already have a 12v Bus.

kindest
Allison
 
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