# Which type of oscillator should I use?

I want to make induction heater. So I want to make oscillator for this. I want to make oscillator with transistor, inductor, resistor, diode and capacitors but not IC, relay switch, op amps etc. Which oscillator should I make?

The required frequency of oscillator is from 15-50 kHz.

• So you want a 10,000 watt oscillator? – analogsystemsrf Apr 17 '19 at 13:04
• @analogsystemsrf i want to make oscillator for induction heater to melt aluminum cans – Maha Yuddha Apr 17 '19 at 13:39

There are a lot of options, but here are a couple of examples:

The first (which is really a pulse generator), from Unijunction Transistor, shows that there are three outputs that can be taken: VC1 (sawtooth), VB1 (positive pulse) and VB2 (negative pulse):

$$T = \frac{1}{f}= R_3Cln\left(\frac{1}{1-\eta}\right)$$

For a 2N2646 Unijunction Transistor, the intrinsic stand-off ratio η as 0.65, as stated in the data sheet.

An example of an astable multivibrator using emitter-coupled oscillators can be found in Electronics Tutorials - Astable Multivibrator

The periodic time is given by:

$$T = t_1 + t_2$$

$$t_1 = 0.69R_3C_1$$ $$t_2 = 0.69R_2C_2$$

If

$$R_2 = R_3$$

and

$$C_1 = C_2$$

then the frequency of the resultant symmetric waveform is given by:

$$f= \frac{1}{T} = \frac{1}{1.38RC}$$

I, myself, looked into the subject of oscillators recently, and I found some which used only discrete components and came up with a number of options, which I listed in my blog, Swingers.

• Can multivibrator provide the 15-50 khz frequency? – Maha Yuddha Apr 17 '19 at 6:55
• Yes, if you chose appropriate values for C1 and R2. I'll update my answer with some equations shortly – Greenonline Apr 17 '19 at 7:59
• thank you for your answer – Maha Yuddha Apr 18 '19 at 16:14