Help with building CCO?

[mikebg]

My hobby is whatever I happen to be interested in within any 2 week time span.

What does it mean by audio processor?

In original circuit diagram of HOUNDOG, the audio processor is simply a zummer, but you can make BFO (beat frequency oscillator) as in the CCO circuit.

[nabiul]

I'm now trying the modified cco configuration that you made. The original was so sensitive that in order for it to work well, all external wires and the housing would have to be shielded and everything would have to be glued in place. The slightest movement and even the presence of my hand near parts of the circuit would drastically change the frequency.

EDIT: It's even quieter than the original and not as sensitive.

[mikebg]

Hi mikebg. You have not given me your opinion on TARSOS.

Maikl, TARSOS is an incompetent project. Because of very low RF gain, it can not have good sensitivity. The circuitry shows bad style of the author. He has not even tried to copy the good working blocks from other projects. A smart designer should seek to replicate good technical solutions created before him. No need to reinvent the wheel.
If you want proof of these assertions of mine, you should write the block diagram of TARSOS, as I suggested in post #40 . Then the participants in this forum will start to reflect on its shortcomings.

[maikl]

Maikl, TARSOS is an incompetent project. Because of very low RF gain, it can not have good sensitivity. The circuitry shows bad style of the author. He has not even tried to copy the good working blocks from other projects. A smart designer should seek to replicate good technical solutions created before him. No need to reinvent the wheel.
If you want proof of these assertions of mine, you should write the block diagram of TARSOS, as I suggested in post #40 . Then the participants in this forum will start to reflect on its shortcomings.

mikebg thanks for the reply.But when I had more time I create TARSOS.Just to see (some praise,some say bad).Parts are not a problem just a little free time.

[mikebg]

Patern Mikebg has small mistake (short-circuit between "lm" and "rg"). These dots near coils (L2A - L2B) will be inconvenient also.

Chris, dots near to coils show the phase of connection. Coils L2A and L2B are connected in series, but in opposite direction as shown in posting #54. They form system TWIN LOOP in which signals from ground and interference sources are subtracted.
Please show where is the short circuit between Im and Re!

[Krzysztof]

I greet Mikebg.
I know for what points perfectly they are near coils and what they mark, this attention was to Nabiul.
I understand symmetrical setting C3 by R3, but with attention on small value R6 in relation to R4 then nothing gives R2 presence in this connection already practically.
It seems me, that between R4 and R6 from audio side should find capacitor.
Beyond this C8 about so large value, amplifier burdens strongly. The whole arrangement be subject on burden by audio what the disregulate causes considerable MD by any manipulations after side of burden.
I would alter a bit arrangement. It it was can was shift on side C8 the Audio pose the circuit of exit of amplifier, give condenser 4,7-10nF between R4 and R6 would tune up to L1.
It it because one great generator was been arrangement this every close relations to him and the test of control gives already undesirable effects this this treats how adventure and experience, and it is not to work in terrain.
Arrangement homodyne from postes # 52 is more more comfortable, easier and calmer.
With respect Chris.

[mikebg]

It it because one great generator was been arrangement this every close relations to him and the test of control gives already undesirable effects this this treats how adventure and experience, and it is not to work in terrain.
Arrangement homodyne from postes # 52 is more more comfortable, easier and calmer.
With respect Chris.

Chris, what machine translator you are using to translate from Polish into English?
Try to use the same translator to translate contrary your post from English into Polish to feel how hard is for participants in this forum to understand what you mean.
I still understand your opinion, but it is based on an intuition rather than the formulas for calculating mentioned components.
Concerning the principle of action, both circuit diagrams are so similar that it can be called "audio frequency amplifier" with regeneration (positive feedback).
View the following circuit diagrams and determine what IC should be used, CD4069 or LM386?

[maikl]

Here's a simple BFO of Scarborough:"Here's something completely different. I'm well known for my electronic designs, and here's one of the classics. It gives good performance and stability for a beat frequency operation (BFO) metal detector. BFO in itself, though, is not very sensitive -- yet it's easy and fun. This metal detector will pick up a 25 mm (1") diameter coin at 90 mm (31"). The design is based on a simple inverter oscillator, which is attached to a Medium Wave radio aerial. When metal is brought near to coil L1, the frequency of the oscillator changes, bringing about a shift in the difference frequency in the MW radio speaker. Solder the circuit and take a wire to the MW radio aerial as shown. This should be screened, with the screen going to -6V (negative). Switch on both metal detector and radio, and tune the radio until a clear heterodyne (a whistle) is heard in the speaker (some heterodynes will work better than others). There will be a "band of silence" at the centre of most heterodynes (a zero beat frequency), and depending which side of this zero beat frequency is tuned in, the tone in the radio speaker will rise or fall at the presence of metal. It will also respond differently to ferrous and non-ferrous metals." Signs of a single coil TX.

[maikl]

In this dizaj between pin3 and pin4 (tl071) added identical coil it was CCO.Two TX coil.There is no TX and RX.Double BFO.The design is not fine if compared to the IB.But it's CCO.With the simplicity of it gives a lot.

[mikebg]

SCO = Sound Coupled Oscillator

This is the principle of SCO (Sound Coupled Oscillator). The feedback path is formed by a microphone and a loudspeaker. There are given proposals for the following modifications in feedback path:
1. To use two equal microphones.
2. To use two equal loudspeakers.
3. To use the loudspeaker instead microphone and the microphone instead loudspeaker.
4. To put a resistor 2K in series with the loudspeaker.
Do we need to experiment these proposals?

[nabiul]

My hand milled pcb using a dremel and a tiny broken drill bit and it all soldered up.

I replaced the 22pF capacitors with 6-40pF trimming capacitors so that I could tune it for maximum sensitivity or something....

A video of it working: http://www.youtube.com/watch?v=2R4NfkeyXVU

The sensitivity of all parts of the circuit is still too high; just bringing any inductor, like my hand, near any parts including the shielded wires going to the coils, causes random frequency shifts which 'locks up' the detector until I disturb the circuit again.

[Krzysztof]

Hi Mikebg.
My translator was for money, can for small?
My second language this French, English I understand only technical from times "Algol", "BASIC for ZX81 and Spectrum" and SN7400.
My intuition has large experience and good bases.
My final receiver superregeneration (positive feedback) was on lamps 6K7 before 40 years.
Unfortunately, was power supply through autotransformer 220/6,3V.
I connected me with year 1930 metal headphones, I based about earthed radiator and leg. Lamp era finished for me so and she began transistor.
I before 30 years made my first BFO on SN7400 and SN7474, he was quite good.
I greet Chris.

[mikebg]

Hi Chris.
From your post I realized that you suffered an electric shock from head to foot by metal headphones.
I also experienced something similar and it by a not powered crystal radio. The reason was that I connected via a capacitor a very large MW antenna not think that atmospheric electricity can load the antenna to a dangerous high voltage. Unfortunately the capacitor was for high operating voltage and instead to damage it, the antenna discharged via my right hand. Since then I am very careful to antenna systems.
My second language is German. For translation between Bulgarian and English I use GOOGLE TRANSLATOR in site http://translate.google.com/#
Recently Qiaozhi showed me excellent work with IMTRANSLATOR in site http://imtranslator.com
Please try them; it is easy.
Yours Mike-BG

[maikl]

Hi nabiul.Of the coil unit to put the two coaxial cables(with one wire in the middle see photo).When you come near hand, micro-inductor L3 will be changed in the earpiece volume (but only in that place).Open and look at headphones, see what the impedance (is given in ohms and write on them).This type of metal detector has a sound discrimination.Pliers need to "see" other sound.A video on your detector does not "see" pliers.It is also an important direction of coil (change in one coil wire layout).There is no need to change C2 and C3.VR1 = 200K put it on the middle position then slowly move a coil until you hear high-pitched tone (this is where the fine-adjust the detector).This circuit elemenatacan withstand up to 15V voltage (add another battery).

[nabiul]

I wanted to use coaxial cables, but I don't think I have any right now. I have to check.

I'm using headphones because I tested both headphones and a crystal earpiece, and the headphones worked better, they were much louder.

I get the best results from these:
The impedance is 18 ohms.
The impedance of the headphones in the video is 24ohms.

I used trimmer capacitors just in case it didn't work properly after I fixed the coils in polyester resin.

The coil direction is correct, if I flip one of the coils around, the circuit stops oscillating.

I'm using 500k for VR1, my coils are not the same as those mentioned in the design, the 200k range isn't enough to tune it properly I think. Even after I position the coils for the high pitched noise, the circuit sometimes gets frequency lock after metal is brought near the coils.