circuit help

[paulyt5966]

hi,i want to build the circuit below and i want it to oscillate at 50hz would someone please tell me what values i would need for r3 r4 c1 and c2 thanks for any help.

 

[Nigel Goodwin]

Presumably you already have the values for 60Hz?.

You need to make the capcitors slightly larger - but the tolerances on electrolytics are so large (usually -50% +100%), that there's no way to calculate anything!.

You should also be aware that these crude inverter circuits don't work well (if they work at all?) - the least of your problems is likely to be the frequency!.

 

[paulyt5966]

dont have values for 60hz either.i was gonna use tantilum capacitors any ideas of the values for the diagram in my previous post or how i could work it out,i just want to build this circuit for experiance.thanks

 

[Nigel Goodwin]

This circuit has been discussed many times here, have a look at one of the previous threads https://www.electro-tech-online.com/threads/ip-core.2695/ which includes values.

 

[Roff]

That circuit is like a flu virus. It is dormant in many places around the world, and surfaces every year or so to wreak havoc on the hobbyist population. There are lots of mutations in the thread that Nigel cited. Some of them may be beneficial. :roll:

 

[bryan1]

Well with the price of small inverters these days being around the price of a beer carton I wonder why people still want to make up crude devices that plainly either don't work or are so inefficient it ends up in total frustration. I've spent a great deal of time looking for an efficient inverter design without sucess and a 400 watt inverter can be had very cheap so why try and re-invent the wheel :shock:

Cheers Bryan

 

[paulyt5966]

sorry i brought this one up guys didnt see it on this site first,had the spare parts so just thought i would build this one,seen some better ones now so will give them a try,its to easy to go out and spend 30quid on a inverter when you can waist endless hours and twice as much money trying to build one,thanks guys.

 

[audioguru]

Watch out for the ratings of store-bought inverters. Their rating is usually for the peak power output for a few minutes. Their continuous power ratings are half.

The inverter you were thinking about building has its capacitors backwards and even if their polarity is correct, they blow-up due to the transistors breaking down and driving huge currents through them.
The circuit isn't an inverter, it's a smoke generator. :lol:

 

[mstechca]

The circuit isn't an inverter, it's a smoke generator.

I will have to agree with audio on this one, because you are trying to provide output in an unusual way. Please understand that if you turn on a circuit, and the output isn't done properly, or the components are underrated (less rating than what they should be), the circuit blows up, and therefore, you have generated smoke, should the input be 120V! :shock:

hi,i want to build the circuit below and i want it to oscillate at 50hz would someone please tell me what values i would need for r3 r4 c1 and c2 thanks for any help.

I still fail to understand why this circuit should be done, just for a 50Hz oscillator when you have no output that indicates that it is a 50Hz oscillator. The output should be an LED, speaker, or connected to an input requiring 50Hz.

as for r3, r4, c1, and c2, look at the R and C's that are connected together. multiply both there values to get the approximate frequency of one output (whether it be logic high or logic low), and do the same with the other R and C. One output is the inverse of the other. The duty cycle is the ratio between how long one output is on with respect to the other output. It is usually expressed in percent. So if R and C are exactly the same, the the duty cycle is 50%.

 

[evandude]

I still fail to understand why this circuit should be done, just for a 50Hz oscillator when you have no output that indicates that it is a 50Hz oscillator. The output should be an LED, speaker, or connected to an input requiring 50Hz.

mstechca, do you know what an inverter is? its input is 12VDC and its output is 120VAC at 50Hz, thus the oscillator. Although, in reality, as audioguru has said, its output would instead just be smoke :lol:

 

[mstechca]

mstechca, do you know what an inverter is? its input is 12VDC and its output is 120VAC at 50Hz, thus the oscillator. Although, in reality, as audioguru has said, its output would instead just be smoke :lol:

sorry, I wasn't thinking of a "power inverter" at the time. I was thinking of a NOT gate :lol:

But still, I can see that circuit configuration is just not the configuration I would use.

Have you checked Harry's Homebrew pages? He has a bunch of circuits (I think under the PSU section) that show you how to get a higher voltage from a low voltage, but the higher voltage is probably DC.

I know (according to Harry's homebrew pages) that you can get a higher voltage by making an oscillator that creates it.

But the simplest way to make a higher voltage is to use a chain of diodes and capacitors in a ladderish circuit fashion. I'm not sure if it is called Cockroft Walton ladder or the Johnson Ladder.

Sorry, but I don't know many people's names.

 

[Roff]

mstechca, do you know what an inverter is? its input is 12VDC and its output is 120VAC at 50Hz, thus the oscillator. Although, in reality, as audioguru has said, its output would instead just be smoke :lol:

sorry, I wasn't thinking of a "power inverter" at the time. I was thinking of a NOT gate :lol:

But still, I can see that circuit configuration is just not the configuration I would use.

Have you checked Harry's Homebrew pages? He has a bunch of circuits (I think under the PSU section) that show you how to get a higher voltage from a low voltage, but the higher voltage is probably DC.

I know (according to Harry's homebrew pages) that you can get a higher voltage by making an oscillator that creates it.

But the simplest way to make a higher voltage is to use a chain of diodes and capacitors in a ladderish circuit fashion. I'm not sure if it is called Cockroft Walton ladder or the Johnson Ladder.

Sorry, but I don't know many people's names.

Cockroft-Walton is a DC-DC converter that will put out high DC voltage at low power.

Our OP is looking for a DC-AC converter (inverter) that will put out high AC voltage at high power.

 

[Nigel Goodwin]

Cockroft-Walton is a DC-DC converter that will put out high DC voltage at low power.

No, it's an AC-DC converter, basically an extended voltage doubler rectifier. Most common use is (or at least was!) for multiplying the EHT in TV sets - usually 8Kv AC in, and 24Kv DC out.

In the UK I've always heard it refered to as 'Walton-Cockcroft' multiplier, perhaps it's another thing that changes as you cross the Atlantic?.

 

[Roff]

Cockroft-Walton is a DC-DC converter that will put out high DC voltage at low power.

No, it's an AC-DC converter, basically an extended voltage doubler rectifier. Most common use is (or at least was!) for multiplying the EHT in TV sets - usually 8Kv AC in, and 24Kv DC out.

In the UK I've always heard it refered to as 'Walton-Cockcroft' multiplier, perhaps it's another thing that changes as you cross the Atlantic?.

My bad (I guess). Most of the ones I've seen run off a 555 timer, so in those the source is DC, but the original one was certainly AC-powered.

 

[Nigel Goodwin]

Most of the ones I've seen run off a 555 timer, so in those the source is DC, but the original one was certainly AC-powered.

The 555 is there to provide the AC 8)

 

[Roff]

Most of the ones I've seen run off a 555 timer, so in those the source is DC, but the original one was certainly AC-powered.

The 555 is there to provide the AC 8)

Of course. It's darned difficult to make a DC/DC converter without first converting the DC to AC - although perhaps you could do it chemically. :?: :?:

 

[akg]

Of course. It's darned difficult to make a DC/DC converter without first converting the DC to AC - although perhaps you could do it chemically. :?: :?:

DC Motor-DC Gen

 

[audioguru]

DC Motor-DC Gen

Then you connect the gen to the motor and it keeps going? :roll:

 

[Nigel Goodwin]

Of course. It's darned difficult to make a DC/DC converter without first converting the DC to AC - although perhaps you could do it chemically. :?: :?:

DC Motor-DC Gen

Clever answer! - but with a fatal flaw 8)

A 'DC' generator actually generates AC, which is then 'rectified' to give DC, this is usually done synchronously using the brushes on the DC motor.

 

[akg]

DC Motor-DC Gen

Then you connect the gen to the motor and it keeps going? :roll:

wow.. thinking of hopkinson's experiment 8)