Or:


Which part of NO don't you understand?


The N or the Ooooooooooooooooooooooooooo?

Looks like a comparator of the DC voltage gained from a mains supply compared to ref of Zener1 , having -ve feedback and the switching a load at a sensitity set by the output VR. 


By NO you might mean Normally Open as per the relay or indeed ca circuit that holds itself off when energised.

The propsed component actual values might help.


Otherwise I`ll admit I`m lost.


Could be an artificial chuckle separator

"one for MAPJ" eh ?  challenge accepted.


I think it is one half of these new circuits to disconnect an electric vehicle charger if the mains voltage goes out of spec. we have to assume that the square IC 1 is a voltage regulator, and the triangular IC1 is a comparator, such that when the positive input is at a higher voltage than the negative input, the output is near the positive rail voltage and near the negative rail voltage otherwise.

The comparator sees the Zener voltage on its negative input, and a DC voltage proportional to the incoming mains on the positive input, and the unregulated DC is on its indecisive input power supply pin.


The two transistors form an un-necessary inverter, and in the B model we would eliminate one transistor and reverse the sense of the comparator inputs. Or maybe the contact state for  mains completely  off is also important...

The diode and cap across the relay coil absorb the EMF of the collapsing magnetic field of the relay coil when the transistor turns off.

The main part I do not understand is the reuse of the label IC1..


M.

What has been bugging me, is why have they connected pin 7 of the op-amp the the un-regulated side of the power supply and not to the regulated side. although for that matter did the relay driver circuity need a regulated supply?  

Clive

well the op-amp/ comparator  will have a reasonable power supply rejection, so the comparison decision is not going to reverse as the op amp supply varies, and I imagine you do not want a situation where the comparator inputs could ever be at a higher voltage than its power supply, or it may not survive power down, if the ESD structures on the inputs are biassed so they start to conduct into the power rails. It rather depends what that thing we assume is a 3 legged regulator is doing.

And we have to remember, it is only a pretty pattern on a mug, it may not be a circuit from any real project at all even if that is the pin out of several common op-amps.


So for  bonus points, do you fancy estimating, with or without computer simulation, at what frequency does the flip flop in this one operate?

You may assume the supply voltage is low enough that you can neglect Vbe reverse break down, and that the transistor Hfe is >>100


M.

Top of ny head I would gues that the answer is dominated by C1 R1 & C2 R2 with a little tweak of Q1 & Q2 characteristis

Should there be a flux capacitor in there somewhere?  ?


Clive

I have just discovered that if you pull the top off the pen that Aico sent me there's a hidden screwdriver ?

On back order since 1985 it seems see here

Nearest real none time reciprocal (=near magical)  device that knows which way time is flowing, is probably the
microwave circulator.

Always had a soft spot for magnets.

mike.

I never managed to get my head around those. Was much happier with 1/4 wave stubs. But that said microwave circulators certainly existed in ship radar transceivers. Luckily they never went wrong.

Clive