electronics-amplifier tutorial

Booster Constant-Current Circuit
Constant-current circuits can be configured to take
advantage of the fact that CMOS regulators consume
a very low current.

If you wish to set constant current value io to a
larger value, PNP transistor Tr1 and resistor R1 can be
added, as seen in Figure 5. This will improve the
input/output voltage characteristics, allowing you to
increase the said current value as a result.
Consequently, under the same conditions as stated
above, that is, an input voltage VIN of 3 V and a
device voltage VO higher than 1V, for example, the
drive capacity will rise from 10 mA (typ.) to 100 mA
(typ.).

The resistors R1 and R2 determine the final charging voltage
and RSC the initial charging current. D1 prevents discharge
of the battery throught the regulator.
The resistor RL limits the reverse currents through ther
regulator (which should be 100 mA max) when the battery
is accidentally reverse connected. If RL is in series
with a bulb of 12 V/50 mA rating this will indicate incorrect
connection.


Transistor constant current Circuit
This is a schematic of the smoke circuit regulator. This is a
constant current regulator. The two 1.5 ohm resistors sense
the current in the smoke elements. If the smoke element
current increases, the base voltage of the 2N3904 increases
and it in turn drags down the base of the TIP122 pass transistor
which reduces the voltage and therefore the current of the
smoke elements. The circuit regulates the current to about 1 amp.
The resulting voltage across the elements is about 6 volts. The
most significant internal voltages are shown in red referenced to
the (-) side of the bridge.

Constant Current for Sensor Excitation Circuit
Abstract:
The MAX1464 can be easily configured to generate constant

current excitation for sensors that is ratiometric to the power supply

voltage for resistive transducer applications. Applications utilizing

sensing elements with high temperature coefficients, TCR, such as

piezo resistive bridges, RTDs, etc. are typically implemented with

constant current excitation. This application note suggests a simple

resistive network that can be implemented to provide a ratiometric

current source for sensor excitation.

Transistor constant current source Circuit
The current source shared by the two transistors is also shown in the

figure. Due to the fact that the forward biased diodes have fixed

voltageVd = 0.7V, the base voltage of the transistor is also fixed at 2.1V

, so is the current Icc, i.e., the circuit can be used as a constant current source

Booster Constant-Current Circuit
Constant-current circuits can be configured to take
advantage of the fact that CMOS regulators consume
a very low current.

If you wish to set constant current value io to a
larger value, PNP transistor Tr1 and resistor R1 can be
added, as seen in Figure 5. This will improve the
input/output voltage characteristics, allowing you to
increase the said current value as a result.
Consequently, under the same conditions as stated
above, that is, an input voltage VIN of 3 V and a
device voltage VO higher than 1V, for example, the
drive capacity will rise from 10 mA (typ.) to 100 mA
(typ.).

The resistors R1 and R2 determine the final charging voltage
and RSC the initial charging current. D1 prevents discharge
of the battery throught the regulator.
The resistor RL limits the reverse currents through ther
regulator (which should be 100 mA max) when the battery
is accidentally reverse connected. If RL is in series
with a bulb of 12 V/50 mA rating this will indicate incorrect
connection.


Transistor constant current Circuit
This is a schematic of the smoke circuit regulator. This is a
constant current regulator. The two 1.5 ohm resistors sense
the current in the smoke elements. If the smoke element
current increases, the base voltage of the 2N3904 increases
and it in turn drags down the base of the TIP122 pass transistor
which reduces the voltage and therefore the current of the
smoke elements. The circuit regulates the current to about 1 amp.
The resulting voltage across the elements is about 6 volts. The
most significant internal voltages are shown in red referenced to
the (-) side of the bridge.

Constant Current for Sensor Excitation Circuit
Abstract:
The MAX1464 can be easily configured to generate constant

current excitation for sensors that is ratiometric to the power supply

voltage for resistive transducer applications. Applications utilizing

sensing elements with high temperature coefficients, TCR, such as

piezo resistive bridges, RTDs, etc. are typically implemented with

constant current excitation. This application note suggests a simple

resistive network that can be implemented to provide a ratiometric

current source for sensor excitation.

Transistor constant current source Circuit
The current source shared by the two transistors is also shown in the

figure. Due to the fact that the forward biased diodes have fixed

voltageVd = 0.7V, the base voltage of the transistor is also fixed at 2.1V

, so is the current Icc, i.e., the circuit can be used as a constant current source

Dual Ramp Generator
The first circuit is a dual ramp generator where the positive
and negative ramps are generated separately. This circuit
was used as a ramp generator for a transistor curve tracer:
the positive going ramp was used for testing NPN transistors
and the negative ramp for testing PNP transistors.


Generating Triangle Waves
In the circuit to the right, we use a separate integrator to
generate a ramp voltage from the generated square wave.
As a result, we can get both waveforms from a single circuit.
The phase relationship shown between the two output
waveforms is correct


555 ramp generator
Again, we are using a 555 timer IC as an astable multivibrator,
or oscillator. This time, however, we will compare its operation
in two different capacitor-charging modes: traditional RC and
constant-current.


Ramp Generator by Schmitt trigger

Precision ramp generator produces a 0 to 5V ramp

Linear Voltage Ramp
To make the ramp of the charging cycle linear with time the

Dual Ramp Generator
The first circuit is a dual ramp generator where the positive
and negative ramps are generated separately. This circuit
was used as a ramp generator for a transistor curve tracer:
the positive going ramp was used for testing NPN transistors
and the negative ramp for testing PNP transistors.


Generating Triangle Waves
In the circuit to the right, we use a separate integrator to
generate a ramp voltage from the generated square wave.
As a result, we can get both waveforms from a single circuit.
The phase relationship shown between the two output
waveforms is correct


555 ramp generator
Again, we are using a 555 timer IC as an astable multivibrator,
or oscillator. This time, however, we will compare its operation
in two different capacitor-charging modes: traditional RC and
constant-current.


Ramp Generator by Schmitt trigger

Precision ramp generator produces a 0 to 5V ramp

Linear Voltage Ramp
To make the ramp of the charging cycle linear with time the

Transistor Schmitt Trigger Oscillator
The Schmitt Trigger oscillator below employs 3 transistors, 6
resistors and a capacitor to generate a square waveform.
Pulse waveforms can be generated with an additional diode
and resistor (R6). Q1 and Q2 are connected with a common
emitter resistor (R1) so that the conduction of one transistor
causes the other to turn off. Q3 is controlled by Q2 and
provides the squarewave output from the collector.


X'tal Oscillator Frequency
This circuit may used as clock frequency for many digital
circuits. I got this circuit from a microcontroller clock generator

555 Pulse Generator
A 555 pulse generator circuit with a difference, the initial

pulse is tailored by additional circuitry to match the duration

of subsequent pulses.

Op Amp Square Wave Generator
This is a square wave generator circuit. The main component

of this circuit is the 741, a general-purpose operational amplifier.

This circuit employs a single power supply Vs that can range

from +5V to +15V.

Changing the pulse width
The previous assembly gives a rectangular signal with a duty

cyclic equal to 50 %. We can need to change it to produce

pulses for example. A simple means is to use a variable RC

circuit and to reshape the signal obtained by means of a

Schmidt trigger , here a CD 4093 which allows to use a wide

range of voltage.

Transistor Schmitt Trigger Oscillator
The Schmitt Trigger oscillator below employs 3 transistors, 6
resistors and a capacitor to generate a square waveform.
Pulse waveforms can be generated with an additional diode
and resistor (R6). Q1 and Q2 are connected with a common
emitter resistor (R1) so that the conduction of one transistor
causes the other to turn off. Q3 is controlled by Q2 and
provides the squarewave output from the collector.


X'tal Oscillator Frequency
This circuit may used as clock frequency for many digital
circuits. I got this circuit from a microcontroller clock generator

555 Pulse Generator
A 555 pulse generator circuit with a difference, the initial

pulse is tailored by additional circuitry to match the duration

of subsequent pulses.

Op Amp Square Wave Generator
This is a square wave generator circuit. The main component

of this circuit is the 741, a general-purpose operational amplifier.

This circuit employs a single power supply Vs that can range

from +5V to +15V.

Changing the pulse width
The previous assembly gives a rectangular signal with a duty

cyclic equal to 50 %. We can need to change it to produce

pulses for example. A simple means is to use a variable RC

circuit and to reshape the signal obtained by means of a

Schmidt trigger , here a CD 4093 which allows to use a wide

range of voltage.

Digital Clock with Alarm Using DS1307
DS1307 is a hardware realtime clock, which works on I2C protocol.
Better graphics using the same old fashioned alphanumeric LCD
(type HD44780). Icons which shows the status for Alarm ON/OFF
state, which gives a nice and cute look to the clock.


PIC Digital Clock Timer
This clock timer uses a PIC16F628 microcontroller to display 3
and 1/2 digit time and control an external load. The clock includes
a calendar with leap year and optional daylight savings adjustments.
The timer output can be set from 1 to 59 minutes and manually
switched on and off. The clock also has a correction feature that
allows an additional second to be added every so many hours to
compensate for a slightly slow running oscillator. The oscillator
uses a common 32.768 KHz watch crystal and the frequency can
be adjusted slightly with the 24pF capacitor on the right side of the
crystal.



PIC Digital Multiple Clock Timer
This circuit uses the PIC16F628 microcontroller to provide 4
timed outputs that can be programmed from 1 minute to 1 week.
An extra 8 bit shift register (74HC164) is used for the 4 timer
outputs and to display four additional indicator lights.



Digital Clock with Timer and Solar Panel Regulator
This is a combination digital clock timer and solar panel charge
controller used to maintain a deep cycle battery from a solar panel.
The timer output is used to control a 12 volt load for a 32 minute
time interval each day. Start time is set using 9 dip switches and
ends 32 minutes later. The 32 minute duration is set by selecting
the 5th bit (2^5 = 32) of a 4040 binary counter (pin 2). The timer
also has a manual toggle switch so the load can be manually
switched on or off and automatically shuts off after 32 minutes.
The time duration can be longer or shorter (8,16,32,64,128,256
minutes etc.) by selecting the appropriate bit of the counter.
The timer circuit is shown in the lower schematic just above the
regulator.

Digital Clock with MM5314N
The digital clock of circuit, has as base one IC, the MM5314N,