Author Topic: My first circuit.  (Read 1626 times)

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Offline moontideTopic starter

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My first circuit.
« on: January 24, 2019, 11:41:55 am »
I was trying to make an ocillator.....  damn, I forgot the load but I was with an analog oscilloscope. 
 

Offline moontideTopic starter

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Re: My first circuit.
« Reply #1 on: January 24, 2019, 12:04:33 pm »
I think there is an interesting startup, but but not going what I wanted.
 

Offline Zero999

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Re: My first circuit.
« Reply #2 on: January 24, 2019, 12:20:14 pm »
What's the pin-out for the transistor? Is it viewed from the front or back? Please use the proper symbols in schematics, in future.

The circuit doesn't look like it'll work.
 

Offline moontideTopic starter

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Re: My first circuit.
« Reply #3 on: January 24, 2019, 12:24:12 pm »
Well, you should have been able to get it.... I'll check
 

Offline moontideTopic starter

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Re: My first circuit.
« Reply #4 on: January 24, 2019, 12:27:02 pm »
Meep
 

Offline moontideTopic starter

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Re: My first circuit.
« Reply #5 on: January 24, 2019, 12:30:39 pm »
I don't understand the circuit but I'm still learning....


Ps random time I hit this site and 200+ users and 1800+ guests... lol.
 

Offline Zero999

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Re: My first circuit.
« Reply #6 on: January 24, 2019, 12:50:35 pm »
It's still not clear, even with the data sheet. Is this the circuit?

What's the supply voltage?
Where did you get the circuit from?

Nothing will happen, the transistor will just smoke, unless the supply limits the current to a safe level.
 

Offline moontideTopic starter

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Re: My first circuit.
« Reply #7 on: January 24, 2019, 01:14:12 pm »
Ok. As far as what I can tell I'm trying to oscillate.

I was trying to go:

Passthrough charged.
Leakage on that.. ramped up to allow proper transister usage.
Depletion of that to restart.....






Like I said, first circuit.
 

Offline moontideTopic starter

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Re: My first circuit.
« Reply #8 on: January 24, 2019, 01:29:25 pm »
That is a new way of looking at it for me. I got the circuit from my brain. The power supply should be considered variable.
 

Offline Zero999

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Re: My first circuit.
« Reply #9 on: January 24, 2019, 01:41:19 pm »
Ok. As far as what I can tell I'm trying to oscillate.

I was trying to go:

Passthrough charged.
Leakage on that.. ramped up to allow proper transister usage.
Depletion of that to restart.....
Like I said, first circuit.
That makes no sense. When the circuit is turned on, Q1 will turn on, as current passes through L1. The collector current will depend on its Hfe. The current will keep increasing, as the field builds in L1. The final steady state collector current will depend on: the power supply's internal resistance or Q1's Hfe and L1's internal resistance. If the power supply doesn't limit the current, to a safe level, Q1 will just burn up. :-BROKE  :palm:

The circuit has no way to go back to its original state. To make an oscillator, the circuit needs to be able to flip between two states.
 

Offline moontideTopic starter

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Re: My first circuit.
« Reply #10 on: January 24, 2019, 10:14:37 pm »
So I hooked it up and there did seem to be an ocillation. Around 10 cycles in decreasing amplitude that repeated. There was also another background pattern. After testing multiple points the patterns remained the same. I was perplexed. Then I tested the power supply as I also realised I had no load..... I damaged the power supply and now it is delivering an oscillated voltage....

I take this as a win! Lol.
 

Offline Zero999

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Re: My first circuit.
« Reply #11 on: January 25, 2019, 09:33:10 am »
Where are you measuring the output?

It's not surprising there's some oscillation with an exponential decay, as you have an LRC circuit. The inductor has a parasitic capacitance, which will resonate with the inductance and energy will be lost in the resistance of the windings, hence the decay.
https://en.wikipedia.org/wiki/RLC_circuit

To make an oscillator, an amplifier is required to cancel out the losses, so the circuit becomes unstamped and oscillates continuously. I'd recommend trying a Colpitts oscillator, as it's very easy to build.
https://www.electrical4u.com/colpitts-oscillator/
https://en.wikipedia.org/wiki/Colpitts_oscillator
 
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