# Relaxation oscillator Noob need education

#### Swedishguy

Jan 25, 2013
12
Don´t laught please need some help about my project what i basically want is a solenoid "electromagnet" That switch its magnetic flux in a Oscillation fashion. Much like a speaker my solenoid is about 1.5 ohm. And to get the oscillation i research about relaxation oscillator and transistor oscillator but i went for the Rel for the of easy build. But i am very noob and i cant get it to work. The pic below show schematic and how i assemble it

Probably i am so noob that my theory is not valid. I want to have the output voltage the same as i take in in order to get stronger or softer magnetic field but i only get 0.04 mv at the output i have an pot to regulate the freq the voltage do increase or decrease in the output some but do not oscillate i think.. i thing i destroyed the ic or i connected it wrong. or it is the wrong circuit all together? hope i have explained my self clear sorry otherwise!

#### duke37

Jan 9, 2011
5,364
It looks as if you have a 1uF capacitor and a 20k resistor for the timing. Have you determined the frequency this will give you?

If you connect the output to a load of 1.5ohm you will ask the op-amp to give out current many times what it is capable of. This may have killed it.

#### Swedishguy

Jan 25, 2013
12
Hello duke yea i have probably killed the IC my calculation with falstad simulation a 1uf cap and a 10k pot willbe around 45hz.. Yea i have seen i some circuit they usa a transistor at the end. But i have seen some use speakers to so i just tested..

the cap in the pic is a 10uf just tested if the cap was dead

#### CDRIVE

##### Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Please explain what you want the solenoid to do. Restated, what are you building?

Chris

#### Swedishguy

Jan 25, 2013
12
What i want simply a magnet to oscillation at a given freq and when i want to bump up the voltage the electromagnet becomes stronger pushing and pulling the magnet like an reverse speaker..

sorry if i explaining bad i am trying my best

best regards

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#### CDRIVE

##### Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
I get what you want to do but I still don't know why. Is this an alternate energy project? I ask because we have a special section for that.

Chris

#### KrisBlueNZ

##### Sadly passed away in 2015
Nov 28, 2011
8,393
The solenoid needs a significant amount of current (hundreds of milliamps, or maybe amps) to produce significant magnetic flux density. If you want to drive it with a sinewave, you really need an audio amplifier, the type that's used to drive a loudspeaker. Then you feed your control sinewave into the Aux input of the amplifier and adjust the volume to get the amount of magnetic field variation you want.

If possible, monitor the output of the amplifier with an oscilloscope to make sure it doesn't go into clipping, and keep an eye on the temperature of the amplifier's heatsink.

#### Swedishguy

Jan 25, 2013
12
it is not a energy project its not that big of an deal it is just an experiment im doing dont want to make signification magnetic flux, It work fine when i put 7 or 10 volts trough. the magnet goes forward and when i revers the poles the magnet goes back. now i just need it to do it faster.

but i thank you all for trying i will continue to learn

#### CDRIVE

##### Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Whether you drive the coil with a sine or square wave the magnet will appear to be motionless at 50 - 60Hz.

Chris

Edit: On second thought the term "stationary" is more apropos.

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#### Swedishguy

Jan 25, 2013
12
explain why? a speaker is not motionless att 50 hz

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#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
explain why?

The motion will be too fast for your eye to track.

Depending on the mass of the magnet, lighting, and the force applied to it may appear to have a ghostly transparent outline.

edit: and that presumes it isn't stuck to the soft iron core.

#### Swedishguy

Jan 25, 2013
12
A speaker is not motionless at 50hz you see it move it ?

#### Swedishguy

Jan 25, 2013
12
Ethier case then i am wrong about the hz then it need to be slower.. that what i want to experiment with from 0 and up. And i have riged it so it don´t stuck to the iron core.

#### CDRIVE

##### Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Your sketch indicates a pendulum of sorts so I'm assuming that you want to see the magnet swing back and forth. 50 - 60Hz is to fast for this. At these frequencies the visual effect will appear as a blurry magnet.

Chris

#### Swedishguy

Jan 25, 2013
12
As i sayd Chris but i would like the circuit to do this to establish to experiment this
to get the right Hz the higher the hz the shorter it oscillation and the lower it oscillate longer

Ethier case then i am wrong about the hz then it need to be slower.. that what i want to experiment with from 0 and up. And i have riged it so it don´t stuck to the iron core.

#### CDRIVE

##### Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
There's another issue that you have to deal with and it's not a minor one. The magnetic force required to push the magnet away from the coil (center equilibrium) will have to be much greater than to pull it toward the coil. You won't be able to suspend the magnet on a string either. Do you know why?

Chris

#### Swedishguy

Jan 25, 2013
12
Well that would be a problem if it was on a string it is not, The mechanical is working the way i like i get my push and pull in my rig. The only thing i need. and would like answers to is to get my circuit to work.. so i can get my Hz the way i like. In my rig if i put volt between 3-12 dc it pushes the magnet forward then when i turn of the voltage the magnet will go back to its original position because the magnet attract to the iron core. but there is at distance from the magnet and the iron core so when i turn back the voltage the magnet goes forward.

so my original question is the circuit.
thanks

#### CDRIVE

##### Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Well that would be a problem if it was on a string it is not, The mechanical is working the way i like i get my push and pull in my rig.

We get quite a few topics like this. When I say "like this" I'm referring to topics where the OP is withholding information. We are not novices here. We know it when we see it.

Second guess... reciprocal engine also called a magnetic piston engine or solenoid engine?

Chris

#### Swedishguy

Jan 25, 2013
12
Im sorry that you think i am withholding information. That is not my intention i am trying to explain the best to my knowledge. And i don´t think you are novices that´s why i am here to begin with to get the word from people that are experience in electronic

and i am a novice and i can´t even begin to say what it can be called. but yea you could call it a solenoid engine but more a electromagnet engine ? solenoid with a iron core is defined like a electromagnet right?

#### CDRIVE

##### Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
FYI, these types of motors are a favorite of model maker machinists. You can watch Youtube for hours and never run out of beautiful examples. Even Tublcain made one. None of them reverse polarity the way you're attempting to do it because it's not practical. The timing is accomplished by a set of points.

Chris

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