In series load schematic

Thread Starter

hilologic

Joined Oct 27, 2016
15
Hello,
I want to made a sensor circuit with the output is in series with its self. See my attachment file for illustration.
self.PNG
Many device configured like my illustration i.e proximity detector and timer.
I just need the example design a blinking lamp.
 

Thread Starter

hilologic

Joined Oct 27, 2016
15
No that I mean,
I will plan to made x-circuit but I still confuse because the load must be in series with x-circuit. I energize the load (contactor) ON and OFF continuesly and then from contactor I connect to lamp.

Thank
 

wayneh

Joined Sep 9, 2010
18,104
That can work but it depends on the load. It needs to remain "off" when the small amount of current needed by your circuit passes through it and goes to ground. So for instance a light bulb that uses 0.5A will be dark with just 5mA running through it.
 

Thread Starter

hilologic

Joined Oct 27, 2016
15
Yes I understand but I do not know how to switching the load. I try to energize the contactor with transistor but I lost power for my x-circuit. If just ON I can use SCR to latch the load. I need the x-circuit able to change the load ON or OFF.
 

AnalogKid

Joined Aug 1, 2013
12,126
You are correct that if the voltage drop across the X circuit is small enough that it does not affect the operation of the load, it might be too small to maintain the operation of the X circuit. For this reason, most circuits like your X circuit have a third wire to GND. In this way, the X circuit is powered from the 24 V at all times, and monitors the current drawn by the load with a very small voltage drop to the load (it can be less than 0.1 V).

1. What is the current through the load?

2. What are the voltage and current for the device being switched by the X circuit contactor?

ak
 

Thread Starter

hilologic

Joined Oct 27, 2016
15
the load is aprox.100mA. The x-circuit only need 10mA. I has tried the load cant energize with 10mA.
The x-circuit core is digital gate 40106 ic.
I plan x circuit need 10mA and 5vdc.
thank
 

ScottWang

Joined Aug 23, 2012
7,501
Your idea has a big problem, that is if the Power is +24V and the load is 24V and then the X circuit will be V_Xcircuit = 24V-24V = 0V, so how come a 0V can be supply the X circuit?
 

ScottWang

Joined Aug 23, 2012
7,501
Nobody said it could. Read Wayne's post above.
Yes, I read it before, and the TS didn't shows the whole picture including proximity detector and timer, maybe have some other else, he also didn't mention that why he want to in series the X circuit and load.
 

GopherT

Joined Nov 23, 2012
8,009
Yes, I read it before, and the TS didn't shows the whole picture including proximity detector and timer, maybe have some other else, he also didn't mention that why he want to in series the X circuit and load.
No, but he is obviously going to end up with a circuit like an illuminated doorbell as Wayne mentioned or he will run into all the problems you mentioned (unless you have an alternative solution to the problems that you identified).

Why does he have to tell us the reason for his constraints? If he didn't have this constraint (series connection), the solution would no require him to post here - learn to trust people sometimes.
 
Last edited:

AnalogKid

Joined Aug 1, 2013
12,126
If he doesn't post a schematic of his circuit, he is obviously going to end up with nothing.

To the TS: I know exactly how to solve your problem. It takes four components and costs less than $1.00.

ak
 

ScottWang

Joined Aug 23, 2012
7,501
No, but he is obviously going to end up with a circuit like an illuminated doorbell as Wayne mentioned or he will run into all the problems you mentioned (unless you have an alternative solution to the problems that you identified).

Why does he have to tell us the reason for his constraints? If he didn't have this constraint (series connection), the solution would no require him to post here - learn to trust people sometimes.
When I tried to designed a circuit for this thread, but I met the problem as I described, and many posters whatever in this forum or Taiwan, sometimes they just describe a prat of whole device and they thought that was enough, but in many situations their thinking have some blind point, so they will leading helpers to a unknown situations as going to the jungle and lost direction over there.

We can't force the TS to do anything, but if he describe some more details to let our helpers to find the ways out then it will be easier and solve the problem more quickly.
 

wayneh

Joined Sep 9, 2010
18,104
I have a wireless-remote-controlled light switch that works this way. It's installed in line along the hot wire, if I recall. Could be the neutral I suppose. Anyway, it will only work if there is a resistive load (a lightbulb) in the circuit. Otherwise there is no power to the receiver.

I learned this the hard way. I wanted this wireless switch to control my hot tub jets, so I could turn them off without getting out of the tub. Otherwise they spray all over the bathroom once the water level drops below the jets. Stupid design. My plan didn't work at first, with just the hot tub connected. I suppose there is some relay that controls the jet motor, and that didn't draw enough current to make the receiver work. I had to wire an outlet to be on the same switch, and then I plugged a decorative bulb into that outlet. Then I joined a nice gym with a great spa and never use the one at home.
 

GopherT

Joined Nov 23, 2012
8,009
I had to wire an outlet to be on the same switch, and then I plugged a decorative bulb into that outlet. Then I joined a nice gym with a great spa and never use the one at home.
swap the "decorative light" for a lava lamp and you'll have a whole new groovy experience that the gym will never match.
 

hp1729

Joined Nov 23, 2015
2,304
Hello,
I want to made a sensor circuit with the output is in series with its self. See my attachment file for illustration.
View attachment 114334
Many device configured like my illustration i.e proximity detector and timer.
I just need the example design a blinking lamp.


in series means the same current must flow through both. The x circuit must be ale to handle the 100 mA. I suggest swapping the x-circuit and the load, So the CD40106 just needs a transistor on the output.
 
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