Ramp Generator Circuit

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

The ramp is generated by a constant charging current into

capacitor CRAMP, which is connected between ground and

the noninverting input of op amp IC1, configured as a

voltage follower. The current through RRAMP is the charging

current, kept constant by forcing the voltage across RRAMP

to equal the reference voltage from IC1. One side of RRAMP

is connected to CRAMP, and the other side to the reference

output. In turn, the ground terminal of the reference IC connects

to the op-amp output, which provides a low-impedance replica

of the voltage across CRAMP

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

capacitor must be charged from a constant current. R1 is

replaced with another PNP Q3, which implements a constant

current source. Q3's base voltage is fed from a diode drop,

leaving just a single resistor R1 to vary the charging current,

and hence frequency of oscillation.

Pulse Generator Circuit

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.

PWM Generator Circuit

PWM Generator with Current Limit Circuit


PWM using 555

IC1 astable gives a fixed square wave at pin 3, C1 and R1 derive
uS trigger pulses from IC1 and this will trigger IC2 monostable or
single shot, the voltage at pin 5 of IC2 will change the pulse width
output of IC2, to get it working all the three RC combinations
have to be figured out


A Simple PWM Circuit Based on the 555 Timer

The 555 timer in the PWM circuit is configured as an astable
oscillator. This means that once power is applied, the 555 will
oscillate without any external trigger. Before the technical
explanation of the circuit, let's look at the 555 timer IC itself.


PWM generator

Here is an assembly very simple to get an oscillator giving
a fixed frequency signal but variable duty cycle. It can - after
amplifier transistor - serve to control the rotation speed of a motor
with direct current or to adjust the power of a dew-heater. We use
once again a logic gate of a CD4093 circuit.


Opamp PWM Generator Circuit

This uses the LM324, a 14-pin DIL IC containing four individual
op-amps and running off a single-rail power supply.
The sawtooth is generated with two of them (U1A and U1B),
configured as a Schmitt Trigger and Miller Integrator, and
a third (U1C) is used as a comparator to compare the sawtooth
with the reference voltage and switch the power transistor.


PWM Generator Circuit by Digital register method

an example circuit using the digital comparison method
when a microcontroller is available to set the 4-bit digital register
value. A write strobe is required from the micro to latch the 4 data
bits into the register. The 74HC161 counter is free-running,
the frequency being set by the 74HC14 oscillator section, where
it is roughly f = 1/(6.3RC). The resulting frequency of the PWM
signal will be 16 times less than this counter clock frequency,
since it requires 16 pulses to complete one "revolution" of the
counter. With R=2k and C=1nF this results in a counter
frequency of approximately 80kHz which will result in a PWM signal
frequency of 5kHz.


0 - 100% PWM generator Circuit

The next circuit I found is actually a concoction of 2 separate
designs that cunningly come together to form a 0 - 100% PWM
generator. The first stage uses a single 555 timer to generate a
constant saw tooth waveform.

Yes I know that we don’t want a saw tooth but it can be easily
converted to PWM. If you look at the saw tooth you can see
that it is a wonky triangle, but wonkyness aside it has a fat bottom
and a thin top (just like most triangles).