36 Threads found on edaboard.com: Hf Oscillator
Hello I have many IF-transformers (cans) taken out from transistor radios and CB but I do not know their resonating frequency.
I have access to a spectrum analyzer so I would like to make an HF oscillator to find their frequency.
I have tried different oscillators from the internet but I could not make anyone oscillate.
I do not want a crysta
RF, Microwave, Antennas and Optics :: 22.11.2009 06:18 :: neazoi :: Replies: 3 :: Views: 1319
I've build this oscillator and it works perfect but I need to switch the positions of the 2 variables capacitors to have the 15p-280p grounded (I have some Hf signals coming from antenna) The problem is when I permute the two CVs, I dont have the same frequency range ?? What can I do without changing the circuit? Thanks
RF, Microwave, Antennas and Optics :: 27.05.2007 09:35 :: falcone :: Replies: 3 :: Views: 1891
I need some help..Ive been trying to build a RF amplifier for 12MHZ .But ive had some problems driving power.
The basic oscillator is a colpitts one with crystal using a BJT 2N2222 .Output is taken from BJT colector.The bjt colector also has a choke tied to +Vcc.But I need to boost output power. Just 1 BJT isnt enough for getting 180Vpp and 20
RF, Microwave, Antennas and Optics :: 12.08.2007 16:01 :: meridio :: Replies: 2 :: Views: 1114
Thanks at first.If i want to let it oscillate in 500KHz(LF) or 900MHz(HF),How can i caculate,and any formula to evaluate the Zin for negtive impedence and C1,C2?My E-Mail:John_li3000@sohu.com,look forwards to your reply.
Analog Circuit Design :: 28.01.2008 02:08 :: John_li :: Replies: 13 :: Views: 2375
You will be best off by using inductive coupling. Especially if everything is in a large metal box.
In the EU there are rules on unintentional radiation in the HF ISM bands. You can exceed these with just tens of watts of power.
RF, Microwave, Antennas and Optics :: 19.05.2008 18:06 :: flatulent :: Replies: 11 :: Views: 1742
Hello I am building a QRP (CW) transmitter tor the HF bands 160m to 10m and I need an amplifier to drive my oscillator so I can get 1-2W max out.
I have found this circuit (picture at the bottom) and I have built the oscillator but I need to eliminate the interstage transformer (capacitive coupling)
I have managed t
RF, Microwave, Antennas and Optics :: 27.12.2009 13:51 :: neazoi :: Replies: 4 :: Views: 2337
I have built a hf start module for a tig welder, its basically a high voltage radio frequency spark gap oscillator driven by a car ignition coil, its aim is to start the arc from the electrode to the work esp on low welding voltages.
It works well on my dc output alternator generator welder, however I tried this device on a ac stick w
Hobby Circuits and Small Projects Problems :: 15.03.2010 03:44 :: dr pepper :: Replies: 1 :: Views: 4260
It depends on the rate of charge you plan. Considering 0.1C (1/10 th of battery rated amperage), ie, 10A, you need a power supply capable of supplying 13.5V 10A. This is 135W of output power. You could use flyback or forward here, although at this power, you should look towards half-bridge or two-switch forward.
For half-bridge, you need a
Power Electronics :: 13.07.2010 06:53 :: Tahmid :: Replies: 2 :: Views: 3596
+/-5V on 50 Ohm means a +/-100mA delivering capability, are you ready for some complexer output stage to build? I think on "Composite amplifier" some discretes & HF Op + DC compensating low speed precision Op...
Your spec of less as 5ns for both edges isnt so full trivial (peak to peak 10V & 3dB bandwith of min. 70 MHz, even if your fre
Hobby Circuits and Small Projects Problems :: 16.07.2010 13:36 :: karesz :: Replies: 13 :: Views: 1784
Could anyone suggest a method of generating a stable 13.56 MHz sine wave? I have used a VCO in the past for a UHF application but I am trying to stay clear of using smt.
I've looked into the possibility of using a colpitts oscillator but have not built one in the past... Are they pretty stable?
RF, Microwave, Antennas and Optics :: 22.09.2011 09:08 :: 640badams :: Replies: 2 :: Views: 446
I am trying to electronically alter the capacitance in a specific point in an analogue circuit, for example an HF oscillator. A varicap is not the solution I look for.
A switched capacitance bank could be one solution, but multi switch relays are needed
Electronic Elementary Questions :: 12.01.2012 06:34 :: neazoi :: Replies: 8 :: Views: 1264
Hi every one,
I do not know if I am in right topic section. I need some schematic circuit diagram of an HF Plastic welding machine (for creating Photo Albums). I want to assemble one for me by using FU 501 triode as the main oscillator/output tube.
Service Manuals, Requests, Repair Tips :: 24.01.2012 13:34 :: Saba Khan :: Replies: 0 :: Views: 906
Hello I alter the frequency of an HF (1-30MHz) crystal oscillator using an MV209 varicap.
I need to replace it with a greater capacitance range varicap to increase the tuning range, as much as the crystal permits it. Which one should I use?
1) 9.5v maximum tuning voltage
2) junction operating temperature more than 80C, since it
Analog Circuit Design :: 14.02.2012 19:17 :: neazoi :: Replies: 0 :: Views: 384
As vimalkhanna says, what frequency, power, supply voltage, etc?
Building a real class C oscillator can be very difficult to almost impossible. Real class C (with conduction angle < 120 degrees) is sensitive to envelope instability.
Because of the harmonic-rich content of the current waveform, getting the correct termination for the harmo
Analog Circuit Design :: 26.02.2012 12:33 :: WimRFP :: Replies: 12 :: Views: 1621
can any one help me to find 27 MHz with crystal oscillator Experienced and trusted...
Go and find an old 27 MHz crystal controlled CB radio, there are sources of CB radio circuit diagrams on the net
do some googling :) most of the circuits used a colpitts oscillator
what is the di
RF, Microwave, Antennas and Optics :: 07.03.2012 18:46 :: davenn :: Replies: 5 :: Views: 814
Yes; Google "oscillations and regenerative amplification using negative resistance devices" and you will find a good paper that includes a -R audio oscillator.
And here is a practical application of the principle at HF;
RF, Microwave, Antennas and Optics :: 09.04.2012 02:15 :: krp :: Replies: 1 :: Views: 624
The above links show how to design an oscillator for a certain configuration, but I was unable to see an example of how this theory can apply to the design on a practical circuit such as a colptts or a hartley oscillator.
Does anyone know where I
RF, Microwave, Antennas and Optics :: 08.05.2012 05:49 :: obrien135 :: Replies: 10 :: Views: 1087
can you explain more about RFC?
RFC derived from Radio Frequency choke . it will be open circuit instead of our desired frequency . it will use to prevent from unwanted interferences between our sources .
and how to check oscillator, if it's good condition ?
Do you have access to an oscilloscop
Hobby Circuits and Small Projects Problems :: 01.07.2012 12:00 :: goldsmith :: Replies: 6 :: Views: 1845
Hello I am trying to make a simple RTTY oscillator for the HF bands that can accept 1.2KHz and 2.2KHz audio tones.
Can this be done using a quartz crystal for better stability, or the crystal does not allow so much deviation?
Also are there any sources of such a schematic?
RF, Microwave, Antennas and Optics :: 29.06.2012 06:00 :: neazoi :: Replies: 0 :: Views: 185
Yes, this reduces the Q of the inductor and also sets the impedance at higher frequencies as resistive.
In the old days of valve/tube power amplifiers it was common to put such a network (with higher inductance) in the plate leads of HF power amplifiers to reduce the probability of spurious oscillations at VHF.
RF, Microwave, Antennas and Optics :: 23.02.2005 01:30 :: flatulent :: Replies: 1 :: Views: 632
I want to design a wideband VCO 32-110MHz,Can you give me some examples about HF wideband VCO?Thank you very much
RF, Microwave, Antennas and Optics :: 16.12.2005 07:38 :: liberal :: Replies: 5 :: Views: 1498
The problem is tricky - he wants to have consumption about 3 microwatts .
So oscillator must be very efficient , that put restriction on using UHF, which is preferred for such communication - antenna lenght could be very small)
I think you can experiment with ferrite antennas on LF-HF band to keep power consumption low.
Or may be usltras
Hobby Circuits and Small Projects Problems :: 20.01.2006 11:09 :: artem :: Replies: 2 :: Views: 799
xorcise is right about the oscillator frequency for 50Hz output.
But I don't think the inverter will be running at 50Hz. That is the output frequency, which is really just a modulation for the HF signal.
I will try to dig up some schematics.
Microcontrollers :: 06.11.2007 12:22 :: VVV :: Replies: 12 :: Views: 8244
In the nature you can find much higher frequencies...
Ask only an Astro physician :-) or radio astronomes ..._ Both are working up to 10th of GHz (and beyond).
But more practicables_for us: google pls simple for HF XTAL or SAW oscillators...
The best are i.e. in an SMD package from 7x4 mm & up to 550MHz, but I know that older profesional X
Analog Circuit Design :: 30.03.2010 08:25 :: karesz :: Replies: 1 :: Views: 454
It might be a Russian made HF transistor..
RF, Microwave, Antennas and Optics :: 01.04.2011 11:54 :: BigBoss :: Replies: 9 :: Views: 724
welcome to EDAboard.
such a circuit needs higher volateg than 35V AC.
please check some emergency lamps ike SUNKA make , a chinse brand , i suppose.
the high voltage AC used there measures 150 to 200V ?at 50KHz , may be.
thus you need to create a 50KHz oscillator and have a booster circuit with a ferrite cored transformer.
then these Ph
Analog Circuit Design :: 02.04.2011 15:38 :: mvs sarma :: Replies: 9 :: Views: 1376
RF, Microwave, Antennas and Optics :: 16.09.2011 03:51 :: vfone :: Replies: 8 :: Views: 455
A series inductor will block/filter HF noise (ignition signals)
Electronic Elementary Questions :: 28.01.2012 15:36 :: klystron :: Replies: 15 :: Views: 534
In the HF frequency range higher Q is a must for inductors as it represents less dissipative loss.
For the best results air core inductors are often silver plated, but also enamel covered copper wire will do the job as copper inductors has acceptable Q. Try to make your own 50nH inductor, see details
Analog Circuit Design :: 02.02.2012 03:01 :: mister_rf :: Replies: 6 :: Views: 604
Does anyone know a good supplier for general purpose hobby radio ICs like mixers, LNAs, modulators, etc.? Maybe a supplier for amateur radio hobbiests? Digikey and others only seem to sell the specialty stuff.
Specifically I'm wanting to build a circuit that will downconvert a narrow-band signal from 3MHz - 30MHz to a few tens of kilohertz (say
Analog Circuit Design :: 26.02.2012 19:12 :: digiproc :: Replies: 1 :: Views: 292
hello every one.
I find no words to describe my situation.
there is 2 months that I am designing a DRO oscillator in microstrip technology at 10 GHz
I tried the following figure, but without success.
Please, help me, soon my academic defense and I have done nothing yet.
if you know a schema, a list of s
RF, Microwave, Antennas and Optics :: 30.05.2012 21:11 :: LeThalois :: Replies: 0 :: Views: 174
It would really be helpful but I do not have excel installed...
Ok I have tried it. It does not show any spurs below 30 mhz. I choose the range to be 1-30mhz and it shows highlights almost all over the hf band. I may be doing something wrong there, I am a bit confused.
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Electronic Elementary Questions :: 25.07.2012 07:35 :: neazoi :: Replies: 5 :: Views: 497
Thank you all!
What if a class-A amplifier is used? (rarely used on hf) Does this change the situation at all or the same thing applies?
RF, Microwave, Antennas and Optics :: 15.08.2012 15:07 :: neazoi :: Replies: 9 :: Views: 469
mainly mobile battery charger and lead acid battery charger also.
Many of the mobile chargers are based on HV oscillators which are without negative feedback and they only produce an AC wave which is HF and then a rectifier and then applying that to the mobile and then mobile will use it's supply IC to make it useable .
Analog Circuit Design :: 23.05.2013 18:45 :: goldsmith :: Replies: 5 :: Views: 468
I made a HF pedal for my welder with an illuminated footswitch. I wired it up by trial and error, and it sort of works, but I don't know why!
The foot switch makes a circuit for a secondary output primary coil which energizes a spark gap oscillator that generates high frequency bursts of high voltage to help start the arc. The LED lights up whe
Show your DIY :: 21.05.2013 10:12 :: t0m :: Replies: 0 :: Views: 596
In older times, HF sweep generators with large Fmax/Fmin were made based on a high frequency VCO (Voltage Controlled oscillator, for example 170..200 MHz) and a second fixed frequency oscillator (for example 150 MHz). Both outputs are fed into a mixer (functionally a multiplier) and the difference frequency (here 0..30 MHz) is selected via a low p
Analog Circuit Design :: 08.06.2013 06:48 :: WimRFP :: Replies: 9 :: Views: 667