# Hartley oscillator simple project help

Discussion in 'The Projects Forum' started by leonheard, Jul 5, 2014.

1. ### leonheard Thread Starter Member

Jan 8, 2013
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0
Hello!

I need help for my next project... I want to build an hartley oscillator with a resonant frecuency of 9khz
My power supply has 5.2 volts, my LC tank circuit is tuned to resonate at 9 khz ( no problem there I made the taped air coil about 14.15uH and 22uF capacitor) BUT what would be the values for
R1,R2,R3,R4
C1 = capacitor emisor
C2 = capacitor output
C3 = capacitor base

Here is the link of that hartley oscillator.
http://www.electronics-tutorials.ws/oscillator/osc6.gif

I have basic knowledge in electronics

2. ### Alec_t AAC Fanatic!

Sep 17, 2013
5,973
1,135
Where is the tap in relation to the coil ends? Half way between, or ....? Is your 22uF cap non-polarised (since the voltage across it is alternating)?
You could try R1=10k, R2=4k7, R3=2k2, R4=1k, C1=1u, C2=100nF, C3=100nF. However, I couldn't get a simulation of the circuit you posted to work with the coil tap grounded directly. It needed to be grounded via a >1uF cap instead.

3. ### leonheard Thread Starter Member

Jan 8, 2013
48
0
Where is the tap in relation to the coil ends? Half way between, or ....?

its in the middle.

Is your 22uF cap non-polarised (since the voltage across it is alternating)?

it is actually an electrolyte :/ i guess i will need to buy a non polarised one...

However, I couldn't get a simulation of the circuit you posted to work with the coil tap grounded directly. It needed to be grounded via a >1uF cap instead.

Thanks! I didnt know that, how did you know that a >1uF cap needed to be used?

I couldn't get a simulation of the circuit you posted to work

Could you tell me the name of the simulation u use?

4. ### Alec_t AAC Fanatic!

Sep 17, 2013
5,973
1,135
Trial and error. That's the beauty of simulation .
I use LTspice (as do many on this site), a free download from Linear Technology.

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5. ### leonheard Thread Starter Member

Jan 8, 2013
48
0
Trial and error. That's the beauty of simulation

I thought you used maths, formulas etc lol xD

I use LTspice (as do many on this site)

wow! i have that software, i used only 1 time since i didnt know how to use it but now i will learn and use it more often.

Thanks for the help!

6. ### Alec_t AAC Fanatic!

Sep 17, 2013
5,973
1,135
Recommended. Well worth the effort. It takes a while to get familiar with it, but there are good examples supplied, comprehensive Help, and a Yahoo LTspice user group for further help and free additional model libraries to download.

7. ### RichardO Well-Known Member

May 4, 2013
1,341
429
14 uH is an awfully small amount of inductance. I would increase the inductance of your coil and reduce the size of the cap.

I would shoot for a maximum capacitor size of about 1 uF. This allows using a high quality polyester film capacitor. A 1 uH cap would need about 300 uH of inductance to resonate at 9 KHz.

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