electronic assembly

The characteristics of this generator:
Frequency range: 0.02 Hz ... 5 kHz
Setting, either:
- The frequency continuously,
- Duty cycle,
- Ton and Toff separately.
Output amplitude adjustable between 0 and 10 V, 1 Amp
Open collector output, 6 amps.
Small speaker to "hear" the signal.

Furthermore, this generator is simple and economical to produce.

The principle chosen

The purpose of this section is to explain how I designed my generator step. I give you just the small schemes, whose role is to make you understand how it works. The final scheme of the generator and the values of the various components will be given in Part 2.
I opted for the scheme very well known in the astable trigger inverter.

The resulting signal is pretty much balanced (duty cycle = Ton / (Ton + Toff) = 0.5). It varies between just over 0 V and V + is less.
The operating frequency is given by the formula: 1 / (1.39 * R * C *)
It is a basic scheme, we will be able to adjust to change what we want and which we will add more output stages to match the characteristics that I have promised.

Changes in order to resolve what you want:

To change the oscillation frequency "to good" (ie ranges of frequencies), we modify the database schema as follows:

To vary the frequency continuously, using a potentiometer - resistance R 'is used to prevent the gate output is connected with the input resistance is too low:

Now we want to go further, you want to adjust separately Ton (the time during which the output of the gate is "1" all the time) and Toff (the time during which the gate output is "0" all the time ).
To do this, use two potentiometers and two diodes. Toff regulated P1 and P2 regulatory Ton. I represent two resistances: R '1 and R'2, but in fact, one is enough. Also, if we remove R '1, we can have a very small Toff, but Your will be limited by R'2. Similarly, if we remove R'2, we can have a very small Ton, Toff, but will be limited by R'2. Subsequently we will not have to choose which of these two resistors off, because there will be on the front of our generator switch ... I say no more for now :-)
Note that the threshold voltage of the diodes is a defect in this assembly. However, by feeding the doors with a sufficiently high voltage (12 V), these thresholds are not annoying at all.

Finally, we want this time adjust the duty cycle with a single potentiometer. Évolura The duty cycle from less than 1% and 99%. Frequency, for its part, will remain roughly constant.

Different output stages:

First, it will be used to view the status of the output with LEDs. In what follows, the LED1 will light when the output is "off", and LED2 when the output is "on".

If the LEDs are useful for very low frequency signals (below 10 Hz) for low frequencies (20 Hz ... 20 kHz), nothing beats a sound to "see" what comes out of our generator. We use a miniature loudspeaker or headset, you can choose any impedance. To prevent the generator does break the ears to "hear out" we must keep the button pressed.

I promised an open collector output, and although it is! T2 is a power transistor, diode D is a power too - in fact, when the frequency rises, the power dissipated during switching is no longer negligible ... The diode will allow you to use the assembly with inductive loads (motors, ...); it is also a protection if you reverse the polarity of the voltage source that will connect to the output. Indeed, an open collector output will not issue any tension, it behaves like an open switch (during Toff) or closed (during Ton).
This is the great interest of this type of output, it is not bound by the limits of the voltage source contained in the generator. T2 will be a power transistor FAST, even at the highest frequency in our case 10 kHz, making periods of 0.1 ms, it will have ample time to switch. Therefore a maximum switching time of 10 s for T2, and also for T1 (typically a power transistor is more difficult to quickly find a transistor "normal" fast).
Finally, according to the characteristics of the open collector output will be those of T2 and the maximum current tolerable by the output will Icmax of T2 and the maximum permissible voltage across the output will Vbemax of T2.

Finally, describe the output amplitude adjustable. It's very simple, using a power amplifier AOP (like TDA 200x) configured as a follower. Notice that there are two knobs, and you can choose one or the other of these potentiometers with SW. In fact, only P1 is available on the front panel, P2 is an adjustable PCB, which is set for the 5V output and after you touch it more. As, SW, front-accessible, allowing you to choose between an adjustable P1 amplitude or an amplitude of 5V compatible with logic circuits (TTL and CMOS supplied with +5 V).

The electronic diagram

Everything was explained in detail in the previous section. It remains to connect everything together to get the full presentation of our generation.
Note that I divided my generator into 3 parts: the main part, you see below, a module "R" and a module "C".

The module "C" is used to select a frequency range. Here is a diagram of the module "C":

The module "R" sets the rectangular signal at leisure. Indeed, the switch SW2, through its four positions, selects the type of adjustment to be made:
- In position 1, the double potentiometer P1 adjusts the duty cycle signal (P2 is "disabled");
- In postion 2, the dual potentiometer P2 adjusts the signal frequency (P1 is "disabled");
- In postion 3, P1 adjusts the Ton, Toff on P2 and is the Toff which can reach very small values;
- In postion 4, P1 adjusts the Ton, Toff on P2, this time it's the tone that can reach very small values;
This is the module "R":

Note that in this module are two potentiometers are double P2 and P1-P1 '.
If you do not like knobs, you can use two simple potentiometers P1 and P1 'instead of double P1-P1'. The simple potentiometer P1 for adjustment of the duty cycle, and P'1, sometimes that frequency or that of Toff. As for P2, replace it with a single knob simple. In fact, you can replace the upper half of P2 (the half-double potentiometer connecting pins 2 and 7 SW2) by a thread. By using a potentiometer P2 to double just brings a little comfort in use: it can go either side of the frequency chosen by the module "C".
Note that the use of double potentiometers, as I suggest, is more comfortable, less clutters the front of our generation, and should not cost more (the price of 2 double potentiometers should not exceed that of simple three potentiometers and it is even possible that it is cheaper).

The list of components

The resistance values are in Ohms.
If power is not specified, it is 1 / 4 Watt.

According LED1 R1 = - 4.7 K for 2mA - 10mA 1K
According DEL2 R2 = - 4.7 K for 2mA - 10mA 1K
R3 = 1K
R4 = 100 - 2 Watts
R5 = 2,2 K
R6 = 10K
R7 = 10K

All capacitors have a voltage of at least 16 V

C1, C2, ... C7 are chemical-type Radial

C1 = 0.02 Hz range 1000μ
C2 = 0.05 Hz range 470μ
C3 = 0.2 Hz range 100μ
C4 = 0.5 Hz range 47μ
C5 = 2 Hz range 10μ
C6 = 4.7 μ range 5 Hz
C7 = 20 Hz range 1μ

C8 = 470n (marked "474") Range 50 Hz
C9 = 100n (marked "104") Range 200 Hz
C10 = 47N (marked "473") Range 500 Hz
C11 = 10n (marked "103") Range 2 kHz
C12 n = 4.7 (marked "472") Range 5 kHz

D1 = D2 = D3 = D4 = 1N4148
D5 = BYX71 or other power diode

LED1 = What you want. Determines its current R1
LED2 = What you want. R2 determines its current
NB: Do not exceed 10 mA LED current as.

T1 = 2N2222
T2 = The choice is yours! According to the current and voltage you want to max out your OC. Warning! Switching time of up to 10us.

IC1 = CD40106 (CMOS)
IC2 = TDA 200x (eg TDA 2006 recovered from an old HiFi)

P1-P1 '= potentiometer double: 2 * 50K - Type A
Potentiometer P2 = double: 2 * 50K - Type A
Potentiometer P3 = simple - 10k - type A
P4 = Adjustable soldering on circuit - 10K

BP = Pushbutton
SW1 = Single Inverter
SW2 = Switch 3 circuits and rotary positions 4
SW3 = rotary switch circuit 1 and 12 positions

F1 = Fuse fast = intensity that can suporte T2
F2 = Fuse fast, 1A

HP1 = miniature speaker or earphone quelquonque

MISCELLANEOUS:

2 fuse holders

1 medium bell pin 14 IC1

A 4mm black socket for the mass
4mm red socket 1 for output 0 ... 10V
A white 4mm socket for output CO

1 12V 1A regulated

1 box
3 buttons for potentiometers
Two arrow buttons to switch

The offset films

Note: You will find that the offset films and settlement patterns are not reversed, so you need to put the non-printed artwork face against the glass of sunshine.
Here is the artwork of the main part:

Here is the artwork of the module "C":

Note that the switch is soldered directly on the plate, the switch will then fixing the module "C" and will be kept behind the front. So before making this booklet, check your capacitors implanted well (gap between the legs), and especially that they are not too high! Otherwise, it will take them down and bend their legs.

There is no artwork for the module "R". Wiring is to achieve with thread after P1 and P2 are fixed on the front.
At first I thought making a circuit, but the knobs could take place, there shall have been as son as solder for mounting "flying".

The locations of the components

Below is the location of the main generator. As a high current is circulated in T2, I advise you to connect to the socket are ISSUER "Mass" with the big cable (1 mm ² minimum). Even if the mass is already connected to the socket for output 0 ... 10V, I urge you to double the connection, so that no current passes through the printed circuit board. Similarly, use of the large cable to connect the collector of T2 to the socket "exit CO".

Here is the implementation of the module "C":

Photo: (Overview).

The top panel (settings):

Module A:

Module C:

Setting the amplitude:

The front panel (connections):

Testing and developed

First, make the main part of our generator. But do not connect the modules currently "R" and "C". For the tests, instead of the module "R", a solder réistance 100K, and instead of the module "C", solder a capacitor 47μ (note the polarity).
As is the first power of our assembly, for safety reasons, do not connect the +12 V power supply for your generator with a wire, but with a resistance of 22 Ohms.
So when the power is turned, the diodes LED1 and LED2 should flash with a period of several seconds. If not, check your welds, and also check that IC1 and the LEDs are soldered incorrectly.
Now, test the outputs.
To test the speaker, press the button ... You should hear a slight "knock" each time the LEDs light up or s'éteingnent (the frequency is too low to produce an audible sound).
To test the output 0 ... 10 V, connect to a voltmeter, when LED1 turns on, there should be a voltage close to 0V, LED2 lights up when a voltage that changes when one acts on P3 or P4, depending on the position of SW1.
To test the open collector output, use the following small assembly, the components to be added are in red (the resistance of one ohm, which has a power of 2 Watts, serves to limit the current Lorqui the bulb is cold):

Note I use a 21W bulb. If your 12V source can charge 2 amps, use a 10W bulb or less. If you want to use for this test the generator that powers the 12V, take before réistance of 22 Ohms, ie make sure that the current through the bulb will not cross the resistance of 22 Ohms!

The bulb should flash to the beat of LED2.

Now it is fitting to connect the modules to our "C" and "R".

We begin by connecting the module "C" , Instead of the small capacitor that we have for testing. Of course, during all welding operations, the generator will no longer connected to its alimlentation. Attention to the polarity, the module "C" to a terminal +! Replace the mounting power, turning the switch, you should be able to vary the frequency of 0.02 Hz (very slow, the LEDs lit resetent several tens of seconds) to a few KHz. For frequencies above 10 Hz, the LEDs appear to be lit simultaneously. This is the time to listen! Press the button and you hear a sound whose pitch changes when you turn the switch SW3.

Finally, you have to wire the module "R". I suggest you first set P1 and P2 on the front, then, once this is done, connect the module R using the small stiff wire (like what is in the cables to the wall phone jacks). Take your time, you quickly become entangled pencils ... (Hey, speaking of pencils, will be a good idea to print the diagram of the module "R", and make a cross on each link once it is made). Then, connect the module "R" in place of the resistance that had been placed for testing. Turn on, this is how it should behave:

The switch SW2, through its four positions, selects the type of adjustment to be made:
- In position 1, the double potentiometer P1 adjusts the duty cycle signal (P2 is "off") at high frequencies, it seems that P1 varies the brightness of LED1 and LED2, LED1 glows more stronger, LED2 weakly shining;
- In postion 2, the dual potentiometer P2 adjusts the signal frequency (P1 is "disabled");
- In postion 3, P1 adjusts the Ton, Toff on P2 and is the Toff which can reach very small values;
- In postion 4, P1 adjusts the Ton, Toff on P2, this time it's the tone that can reach very small values;

Now that everything is OK, I'll tell you what you can do this generator.

Conclusion - Applications

If you have made my generator, it is on to develop with your edits! Indeed, it can not rise very high frequency (5 kHz), it is not very stable, the precision does not match that of GBF lab, but it has multiple settings that will make a very useful tool .

One might be tempted to change the values of capacitors to go higher in frequency, but do not do it! Components (IC2, T2) will no longer track, and should take precautions to these high frequencies (use shielded cables, take into account the parasitic capacitances, ...). In fact, I wanted a small generator for easy installation and convenient.

Also, this generator can be used for other things, thanks to its open collector output.

You sûrment a mini-drill, but do you have a drive? Well, my generator will be able to serve as a mini-drill drive (if your mini-drill is fed continuously, which most of the time the case). How? Put simply set the power of your mini-drill, the mini-drill, and the open collector output of the generator (note: make sure that the transistor T2 can support the maximum current consumed by the mini-drill, and the supply voltage). Warning! All these elements are polarized! The generator should be set to a frequency range between 50 Hz and 500 Hz (no need to go higher, you will not only increase the heat dissipation in T2 and D5, which lower the yield), and the switch SW2 position "1" for P1 adjusts the duty cycle. Thus, P1 will determine the speed of your mini-drill. It is nothing less than the principle of switching power supplies. The advantage of using such power to vary the speed of the mini-drill is to have a constant torque regardless of speed.
If the drill runs backwards, reverse his son.
If the drill runs at full speed and that P1 appears to be ineffective, the open collector output is surely connected in reverse. The current must go through the terminal "CO out" and exit the terminal "mass".

Finally, for Christmas, this generator can serve as a flasher, for low voltage bulbs. However, you can order bulbs 220 V using a relay, which you plug the coil between the ground and the output "0 ... 10 V," which allows you to adjust the voltage across the relay. Warning! With the relay, do not operate the generator with a frequency too high (2 Hz max), and remember the freewheeling diode