That might be important when using real-life parts. Ive tried Safari and Chrome on a Mac, and Internet Explorer and Chrome on Windows. You might also want to swap the values of R1 and R2 to lower the current. When I try to login to 'multisim live', I repeatedly get a '502 Bad Gateway' error. You need to reverse your varactor so that it is reverse biased so it can act like a varactor instead of a simple diode. That means that your varactor is forward biased. I see that you are using a PNP transistor. 001 uf ceramic for 100 MHz, 0.1 uf at 1 MHz are good values. That would also increase modulation bandwidth a lot.Īlso, I don't think Spice cares, but in real life you should have a bypass capacitor, something like. With a team of extremely dedicated and quality lecturers, multisim student price will not only be a place to share knowledge but also to help students get inspired to explore and discover many creative ideas from themselves. You are only going to be modulating the capacitance across the tank circuit by (probably) hundreds of fempto farads so you can safely couple your varactor with 10 pf or so. multisim student price provides a comprehensive and comprehensive pathway for students to see progress after the end of each module. When you get up to high power Mica capacitors are superior. Ceramic capacitors are most common in RF circuits. In real life the 15 uf capacitor would probably work but for these frequencies we don't use such large capacitors because the construction of such large capacitors makes them not suitable for high frequency use -too much stray inductance is the main issue. You can adjust that after you get the RF oscillator working. The larger capacitor(C2, 300pf or so) along with the 100 k resistor will cause a high frequency roll off of your modulation signal at about 5 kHz. You also need to add that 100k resistor between the modulation source and the varactor. NI Multisim: Advanced circuit design software with simulated components. Either you need to make your tank circuit resonate around 100 MHz or change the cap (C2) to 300 pf. Multisim Live is a free, Multisim 14.1 Help: Multisim 14.2 Help: Use the multimeter to measure AC or DC voltage or current, and resistance or decibel loss between two nodes in a circuit. The capacitor from the emitter to collector that I suggested (5 pf) is good for 60x that frequncey but around 1 Mhz the impedance is probably way too high. The RF oscillator is not oscillating.Īt what frequency do you want this to oscillate? Right now it is around the top of the AM broadcast band in most regions -1.6 MHz.

All I see is 100 Hz which is your modulation. I would expect the L/C circuit to oscillate at about 1.6 MHz. I didn't look closely at the waveform and only took your word for it.

Multisim live