Want to know operation of this Schematic

BradtheRad · Jul 11, 2012

1) What your suggestion on Post #34 circuit? As per that circuit both relay should connect at the same time it connects in alternate way, like one is ON and other is OFF, i am interested to understand logic of this circuit

You can drive the second relay by inverting the signal to the first relay.

You showed progress by drawing your own schematic. I suggest you continue working on that.

Also, there are relays known as double-pole double-throw type (DPDT). These have two separate sets of contacts which would allow you to do what you want, all in one housing.

2) Post 39 Falstad circuit really helps me to understand the operation of the circuit, but that circuit operates on 400 ohms coil resistance of relay, but in my case i am using T7CS5D-24 relay parts from Tyco, its having 1600 ohms coil resistance, what type of modification i have to do to drive this Tyco relay? One limitation is i can not increase the power supply from 24VDC

I used 400 ohms only as a guess.

Since yours is 1600 ohms then it is likely to work on the 21 or 22 V coming from the charge-pump supply.

You should test it to find out what is the minimum voltage that will activate it.

3) Can you suggest me any Op-amp part number which is low cost and perform the operation, what we are looking for in Post #34 circuit.

The op amps can be general purpose. You need to use a type that can withstand 24 V at its pins. The all-purpose 741 may suit.

You have to comply with the specs. For instance, the inputs are not supposed to be exposed to a differential of greater than +5V or -5V. This may or may not occur in your project.

4) This 'Full-wave Rectifier with Smoothing Capacitor' circuit is efficient to generate smooth 24VDC (i mean pure 24VDC)? do you know any such compaq part which perform this action?

This power supply is practically the most popular type on the planet. It is reliable and easy to make, even for beginners.

Compaq may make such a supply however I'm not familiar with Compaq parts lists.

sr_raval · Jul 12, 2012

1) Thanks for appreciation, yes i would like to operate the second relay by inverting the signal of first relay in Post #34 circuit, actually i tried diffrent configuartion by modifying the circuit but i am unable to do that, could you please modify Post # 34 on falstad and post a new falstad link? In case application i dont require 2 contacts thats why i have finalized SPST relay
2) In Post 39 i have tried to change capacitor value to drive 1600 ohms coil of relay, but eventhough i am incresing the value above 300uf, relay should not operate, could you modify that Post#39 circuit for 1600 Ohms relay? (My relay specs are Rated voltage 24VDC, operate voltage 18VDC, release voltage 1.2VDC, coil resistance 1600 ohms 10% tolerence, rated coil power 360mW
3) Withstand voltage means supply voltage of op amp? can you elaborate more on this " For instance, the inputs are not supposed to be exposed to a differential of greater than +5V or -5V. This may or may not occur in your project."
4) Actually i am more interested to impant readymade 24AC to 24VDC power supply module, if i will get it in low cost
5) On Post#39 circuit, i found that first op amp works on 28VDC and second op amp work on +- 15VDC, i am unable to understand reason why you did that? because i think both op amp are operate as voltage comparator mode right? and one more thing cant we operate both op amp on 24VDC only, if its possible what are the necessary changes require in Post#39 ciruit? why i am asking this because if both op amps operates on diffrent voltages then i have put extra circuit for that voltages for 28VDC and +-15VDC, it increase the board size and cost of the circuit, let me know your thoughts on this.

BradtheRad · Jul 12, 2012

1) Thanks for appreciation, yes i would like to operate the second relay by inverting the signal of first relay in Post #34 circuit, actually i tried diffrent configuartion by modifying the circuit but i am unable to do that, could you please modify Post # 34 on falstad and post a new falstad link? In case application i dont require 2 contacts thats why i have finalized SPST relay

I do not know of any way to turn off a SPST relay by energizing the coil.

I get the impression that your second relay is supposed to be on when there is no power going to it. This does not happen with a SPST relay.

You may have to consider using a double-throw relay. Use the normally closed contacts if that is what you need.

2) In Post 39 i have tried to change capacitor value to drive 1600 ohms coil of relay, but eventhough i am incresing the value above 300uf, relay should not operate, could you modify that Post#39 circuit for 1600 Ohms relay? (My relay specs are Rated voltage 24VDC, operate voltage 18VDC, release voltage 1.2VDC, coil resistance 1600 ohms 10% tolerence, rated coil power 360mW

My simulation works when the capacitors are under 100 uF. Notice the charge does not vary more than a fraction of a volt. That is adequate in this case.

3) Withstand voltage means supply voltage of op amp? can you elaborate more on this " For instance, the inputs are not supposed to be exposed to a differential of greater than +5V or -5V. This may or may not occur in your project."

Seeing 5 in my book was a misread of small print by me. It is +15 or -15V when supply V is at the maximum recommended + and -30V. (I have often fed an op amp input volt levels which had more than 5V difference without a problem, but I also have not often powered an op amp from greater than 15V, and I have not often used a bipolar supply.)

The important spec is that the input volt levels should not exceed supply rails at either polarity.

This is where you will have to experiment. It is a vital stage in developing a project like this.

Your success in the electronics field requires that you discover what are the limits of the components you build with.

In other words, it's better if components go bad in the lab, rather than in someone's home.

And you must experiment and learn by your own initiative. There won't always be someone to help you in a tight spot.

4) Actually i am more interested to impant readymade 24AC to 24VDC power supply module, if i will get it in low cost
5) On Post#39 circuit, i found that first op amp works on 28VDC and second op amp work on +- 15VDC, i am unable to understand reason why you did that? because i think both op amp are operate as voltage comparator mode right? and one more thing cant we operate both op amp on 24VDC only, if its possible what are the necessary changes require in Post#39 ciruit? why i am asking this because if both op amps operates on diffrent voltages then i have put extra circuit for that voltages for 28VDC and +-15VDC, it increase the board size and cost of the circuit, let me know your thoughts on this.

Both op amps can operate from a single supply in this application.

I forgot to edit specs on one of them. I have now updated the specs so both produce between 2V and almost supply_V+. This approximately describes a 741 type.

Following is the latest revision containing two op amps. Copy and paste it into the Import window of the Falstad simulator.

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sr_raval · Jul 13, 2012

1) actually earlier you said that this second relay might operate as in inverting mode in Post #34 circuit, can you make the necessary changes in this circuit if we want to operate both this relay invertly.
2) yes i have import this java script and checked it, it is working well
3 ) you mean to say i have to order a op amps which should operate on 0 to 24VDC right? what are the other factors i have to concern? yes you are right i need to find out the limit of each components, that is why i am planning to test this circuit first on general purpose board and after that i will move forward to proto type stage
4) Yes i tried to operate both op amps by changing the voltage level
5) one more question, can you design some logic circuit in falstad for CLK pulse input of op amp? actually i thoguht its better if we can take multiple input from diffrent port of microcontroller (for example 3 diffrent port of microcontroller) if all 3 input logic is fullfill then only this logic circuit would generate pulse (5VDC, 1KHz, 50% duty cycle), by doing that we can move forward to next level of redundant design, let me know your thoughts on this

BradtheRad · Jul 14, 2012

sr_raval said:
1) actually earlier you said that this second relay might operate as in inverting mode in Post #34 circuit, can you make the necessary changes in this circuit if we want to operate both this relay invertly.

The falstad simulator code below shows how a relay can be made to shut off when a high signal comes from the left.

An optocoupler will convey a signal, yet nothing is directly connected to the charge pump circuitry.

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x 41 75 169 81 0 24 this source
x 41 109 163 115 0 24 represents
x 89 384 486 390 0 24 switch represents a photodetector

3 ) you mean to say i have to order a op amps which should operate on 0 to 24VDC right? what are the other factors i have to concern? yes you are right i need to find out the limit of each components, that is why i am planning to test this circuit first on general purpose board and after that i will move forward to proto type stage

Seeing that you took on this project I supposed you had a number of op amps on hand. Especially the 741 type because it is popular and inexpensive. It should work in this project.

The main thing to watch is that your device can withstand whatever volt level it will be subjected to. This includes spikes and surges on the supply lines.

4) Yes i tried to operate both op amps by changing the voltage level

That's good.

Did you also test your 24V relay to make sure what volt level it will close at? And what volt level it will open at?

5) one more question, can you design some logic circuit in falstad for CLK pulse input of op amp? actually i thoguht its better if we can take multiple input from diffrent port of microcontroller (for example 3 diffrent port of microcontroller) if all 3 input logic is fullfill then only this logic circuit would generate pulse (5VDC, 1KHz, 50% duty cycle), by doing that we can move forward to next level of redundant design, let me know your thoughts on this

The simulation's clock signal represents 5V pulses continually coming from your microcontroller. The switch represents whether the pulse train is on or off. There is no need for circuitry in between.

The frequency is 1 kHz only because I chose it out of the air. It is a convenient value to use in the simulator. However you should experiment with a range from 2 to 20,000 Hz.

Frequencies above 16 kHz are often preferred because that is higher than humans can hear. It is less likely to create audible buzzing noises.

The capacitors can be adjusted to suit. Their values should be increased if you use lower than 300 Hz.

sr_raval · Jul 14, 2012

In post#39 I'm interested to opearate my relay from 22V to 26V, because I have read from UL document and we should consider such amount of tolerance in this circuit, can you update the post 39 falstad circuit for this voltage range? Because I tried this current circuit but it's not operate more then +- 0.5 tolerance

BradtheRad · Jul 14, 2012

I prefer to use the post #43 version because that has the correct ohm value for your relay coil. It is my latest update.

It appears to work okay on a 26V supply, without any changes. The zener values will still work okay.

If you wish, you can edit the op amp maximum output spec. Observe what is the volt level of its positive supply rail while the simulation is running. Then edit the max output spec to match that.

sr_raval · Jul 15, 2012

By mistake I wrote post 39 but I was talking about post 43 only, I tried to changes different supply but that circuit works on 2 percent positive tolerance but itsnot working on 2 percent negative tolerance, more precisely I'm interested to operate this circuit from 24vdc to 26 vdc supply voltage, and I'm sure it needs some alteration in post 43 circuit, can you make it necessary changes on post 43 circuit.

BradtheRad · Jul 15, 2012

I changed supply voltage by pressing ctrl key, and clicking the '+24' at upper left.

I'm using a Macintosh. It may be the alt key on a PC.

I entered 26 in the box labelled voltage.

This required changing the maximum output levels of the op amps.

Here is the update:

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sr_raval · Jul 16, 2012

Yes i have observe and simulate the circuit on falstad simulator, now post #49 circuit operates with +- 2V tolerence which is good as per my desire.

i have one question with post # 49 circuit, you have changed the op amp voltage also, now first op amp is operates on Min 2 to Max 26V, and second op amp operates on Min 2 to Max 23 V, those supply voltage is mandatory to get +- 2VDC tolerence? because i have changed the op amp voltage and make it Min 0 to Max 24VDC, eventhough circuit is operates from 24VDC to 26VDC and i am getting +-2VDC tolerence, as per my requirement. is it okay if i operates in this manner?

actually as i said earlier i have operates all the compoent on 24VDC only but i need tolerence of +- 2VDC means circuit should operate from 24VDC to 26VDC.

i am going to procure the component to test this circuit on general purpose board(so this component is leaded only) if all is going well in this circuit i move forward to prototype stage, please find the attached BOM with new falstad script with naming, and let me know your inputs regarding specs

BradtheRad · Jul 16, 2012

i have one question with post # 49 circuit, you have changed the op amp voltage also, now first op amp is operates on Min 2 to Max 26V, and second op amp operates on Min 2 to Max 23 V, those supply voltage is mandatory to get +- 2VDC tolerence?

An op amp typically can output close to its supply V. Whether it is 24V or 26V. For completeness it's wise to enter it in the spec table, after changing the supply V.

------------------------

Component values are not critical. 10 percent tolerance is adequate and could be less expene than 1% components you have chosen. It's up to you.

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When the clock input is shut off, C1 will start acquiring a greater charge. It may reach supply V. You selected a 6.3V rating. It needs to be rated higher than the supply V.

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The transistors T1 & T2 are a question mark. They need to turn on sufficiently so that ample current will flow. You selected small-signal NPN and PNP in your parts list BOM. There's a chance these will overheat in use. They will carry surge current when the clock input turns on.

Whatever devices you use must be rated to withstand 26V (or whatever is the highest anticipated V).

You may end up needing medium power transistors.

- - - Updated - - -

i have one question with post # 49 circuit, you have changed the op amp voltage also, now first op amp is operates on Min 2 to Max 26V, and second op amp operates on Min 2 to Max 23 V, those supply voltage is mandatory to get +- 2VDC tolerence?

An op amp typically can output close to its supply V. Whether it is 24V or 26V. For completeness it's wise to enter it in the spec table, after changing the supply V.

------------------------

Component values are not critical. 10 percent tolerance is adequate and could be less expene than 1% components you have chosen. It's up to you.

------------------------

When the clock input is shut off, C1 will start acquiring a greater charge. It may reach supply V. You selected a 6.3V rating. It needs to be rated higher than the supply V.

------------------------

The transistors T1 & T2 are a question mark. They need to turn on sufficiently so that ample current will flow. You selected small-signal NPN and PNP in your parts list BOM. There's a chance these will overheat in use. They will carry surge current when the clock input turns on.

Whatever devices you use must be rated to withstand 26V (or whatever is the highest anticipated V).

You may end up needing medium power transistors.

sr_raval · Jul 16, 2012

1) the Op amp i have chosen is sufficient to perform in our application, you have not comment on the op amp what i have chosen in BOM.
2) Yes i will end up with 10% tolerence of the passive components, but for the prior testing i think lets go in to safer side, this component is only for testing of the circuit preactically.
3) yes you are right but i have selected two types of capacitors because i was not sure which one will give us optimum result, Electrolytic capacitor is okay ? have a look on BOM i have selected electrolytic capacitor also
4) check this part now i have selected T2,T4=BC817-16E6327 and T1= FMMT549, is it okay?
5) yes i tried to keep withstand voltage around 26V

If you have any other comment most welcome

BradtheRad · Jul 16, 2012

For op amps, I would start out using the least expensive ones. This application does not need a fast slew rate, nor low impedance output.

So it's puzzling why you chose op amps that cost $1.96 each.

Electrolytics are okay. The charge on the capacitors is always the same polarity.

R6 (680 ohms) is currently letting through 10 mA, in order to turn the transistors full on in the simulation. However this is probably too much bias current for real transistors. R6 should be increased to 2200.

You should obtain one or more sets of transistors, to experiment with as you develop a prototype. Why not try small signal type first, since it's just possible they will be sufficient? Obtain the medium power type as well, just in case.

Expect to burn up a few components as you get experience.

You should have an assortment of resistors and capacitors. As come in kits of 100 or more. Less expense than buying piecemeal.

These are things one is likely have on hand after getting some experience with simpler projects, before attempting something where people's lives are at stake.

- - - Updated - - -

For op amps, I would start out using the least expensive ones. This application does not need a fast slew rate, nor low impedance output.

So it's puzzling why you chose op amps that cost $1.96 each.

Electrolytics are okay. The charge on the capacitors is always the same polarity.

R6 (680 ohms) is currently letting through 10 mA, in order to turn the transistors full on in the simulation. However this is probably too much bias current for real transistors. R6 should be increased to 2200.

You should obtain one or more sets of transistors, to experiment with as you develop a prototype. Why not try small signal type first, since it's just possible they will be sufficient? Obtain the medium power type as well, just in case.

Expect to burn up a few components as you get experience.

You should have an assortment of resistors and capacitors. As come in kits of 100 or more. Less expense than buying piecemeal.

These are things one is likely have on hand after getting some experience with simpler projects, before attempting something where people's lives are at stake.

sr_raval · Jul 17, 2012

LM358N op amp is okay as per specification please have a look on that, its very cheap.
Then i would freeze those elctrolytic capacitor as per my BOM, but could you please the polarity position as per our circuit?
I am replacing R6 from 680 Ohms to 2200 Ohms.
Yes i am planning to buy extra quantity, we have to consider falsare rate also.
Yes for production we generally purchase 10000 qty but as of now for this test purpose i am gonna buy lesser quantity even if this circuit will give good result then i am gonna move forward to prototype stage and in that i am gonna use SMT component.

BradtheRad · Jul 17, 2012

LM358 appears satisfactory.
It can handle 26V supply.
It can output more than 10mA
It can both source and sink current.

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There is a question whether the right-hand op amp should be powered (a) from the charge-pump, or (b) from the 26V supply.

Method A draws from the right-hand power loop only, independent from the left-hand power loop. This may be desirable. However it requires that you use two separate op amp chips, and that is more expense.

Method B seems as though it should work.
It is wise to experiment with all options to make sure.

-----------------------------

The capacitors all have negative terminal toward supply ground.

sr_raval · Jul 17, 2012

No LM358 handle 32V supply, have a look on this https://www.fairchildsemi.com/ds/LM/LM358.pdf

Yes you are right i will try both options.

And i have just simulate the Post#49 circuit but its operates on 24VDC to 26VDC, but as per UL you need to have tolerence about 2V, means circuit should operates from 22VDC to 26VDC, please make the necessary change in Post # 49 circuit.
By mistake i wrote 24VDC to 26VDC. please make the necessary change in the Post#49 circuit so it can operates from 22VDC to 26VDC supply.

BradtheRad · Jul 17, 2012

Yes, LM358 can handle up to 32V.

If the supply is reduced to 22V, then that means the relay gets 18 or 19V.

Since the relay is rated for 24V, it's possible the relay will not activate.

You can examine this yourself by changing the supply V at upper left (in the simulation).

Therefore to comply with UL specs, you must either:

(a) change to a 18 or 20 V relay, or

(b) change to a 28 V power supply, or

(c) be lucky enough to have a 24V relay that activates down to 19 V.

sr_raval · Jul 18, 2012

Yes you are right but the relay which i have select operating voltage of that relay is 18VDC so i guess relay is not an issue and it has to operate from 22V DC, let me know your thoughts on this.
So do we need to make any necessary changes if we want to operate relay from 22VDC to 26VDC? kindly post the updated version of Post#49 circuit
My relay datasheet is https://www.te.com/catalog/pn/en/2-1393190-8
Do let me know if you require any other information regarding relay.

BradtheRad · Jul 18, 2012

The relay is rated 360 mW.
24V
1600 ohms

At 24 V, it results in 15 mA activation current.

There is a good chance it will not operate in your project, if you apply 22V supply at the left.

sr_raval · Jul 18, 2012

so any other soulution how we can operate the circuit from 22VDC to 26VDC because its basic requirement from UL.

Is it possible to design a circuit such way : 24Vac -15%= 20.4Vac to 24Vac+10%=26.4Vac

because i am going to convert 24VAC in to 24VDC

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Want to know operation of this Schematic

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