12V Low side and High side PWM Motor Light Controller

12V Low side PWM Motor/Light Controller

12V High side PWM Motor/Light Controller

These two schematics are variations on addition PWM circuit that I designed. The diagrams are for 12V operation alone and there are aerial ancillary (common ground) and low ancillary (common +12V) versions. The low ancillary adaptation of the ambit uses an N Channel FET, the aerial ancillary adaptation of the circuit uses a P Channel FET. N Channel accessories tend to handle added accepted than P Channel devices, they are additionally beneath expensive. The aerial ancillary adaptation of the ambit is advantageous back one ancillary of the bulk has to be grounded.

This Circuit can about-face a adequately aerial bulk of current, an IRFZ34N MOSFET can handle over 35 Amps if affiliated to a able calefaction sink. Higher ability FETs, such as the IRFZ48N or IRF1010Z can be commissioned if alike beyond currents are required. It is additionally accessible to affix assorted FETs in alongside for alike added accepted capacity. Always use thermally conductive grease amid the FET and the calefaction sink, and bethink that the calefaction bore is electrically live.

Inductive endless (motors) may crave appropriate affliction back they can accomplish ample voltage spikes that can accident the MOSFET. Replacing the 1N4002 with a fast accretion diode may advice blot the about-face voltage bang back active an anterior bulk such as a motor. If you use these circuits for abstracts with electric vehicles, be abiding to install a ambit breaker in alternation with the battery, the ambit breaker should be accessible to ability by the driver. This is abnormally important due to the actuality that back MOSFETs fail, they generally abbreviate out, abrogation the motor on at abounding speed.

Note that the pwm ascendancy has an adverse aftereffect on these two circuits, the low ancillary adaptation is on with a aerial pin 7 achievement voltage and the aerial ancillary adaptation is on with a low output.

The inductor on the aboideau ancillary of the ability MOSFET transistor can be a ferrite bean or a few turns of wire captivated about a 10 ohm, 1/4W resistor. The purpose of this allotment is to anticipate RF oscillations from occurring in the MOSFET circuitry.

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AM Transmitter Double Side Band

AM Transmitter Double Side Band

The ambit of AM transmitter is advised to address (amplitude modulated) DSB (double ancillary band) signals. A articulate AM arresting consists of a carrier and two symetrically spaced ancillary bands. The two ancillary bands accept the aforementioned amplitude and backpack the aforementioned information. In fact, the carrier itself coveys or carries no information. In a 100% articulate AM arresting 2/3 rd of the ability is ashen in the carrier and alone 1/6th of the ability is independent in anniversary ancillary band.

In this transmitter we abolish the carrier and transmitt alone the two ancillary bands. The able achievement of the ambit is three times that of an agnate AM transmitter.

Op Amp IC741 is acclimated actuality as a microphone amplifier to amplify the articulation best up by the condenser microphone. The achievement of the op amp is fed to the bifold counterbalanced modulator (DBM) body about four IN4148 diodes. The accentuation akin can be adapted with the advice of preset VR1.

The carrier is generated application clear oscillator active about BC548 transistor T2. The carrier is added amplified by transistor T1, which additionally acts as a absorber amid carrier oscillator and the counterbalanced modulator. The alive abundance of the transmitter can be afflicted by application crystals of altered frequencies. For multi abundance operation, alternative of altered crystals can be fabricated application a selector switch.

Ths achievement of the DBM contains alone the artefact (of audio and carrier) frequencies. The DBM suppresses both the ascribe signals and produces bifold ancillary bandage suppressed carrier (DSBSC) at its output. However, back the diodes acclimated in the counterbalanced modulator are not absolutely matched, the achievement of the DBM does accommodate some balance carrier. This is accepted as carrier leakage. By adjusting the 100 ohm preset VR2 and trimmer C7 you can absent the carrier leakage.

To accept DSB signals you charge a exhausted abundance oscillator to reinsert the missing carrier. If you don’t accept a exhausted abundance oscillator, or appetite to transmitt alone AM signal, acclimatize preset VR2 to aperture some carrier so that you can accept the signals on any accustomed radio receiver. In AM approach 100% accentuation can be accomplished by adjusting preset VR1 and VR2.

X1 – 8+8 Turns Bifalar 24 SWG On TV Balune Core
X2 – Primary 12 Turns, Secondary 4 Turns. 24 SWG on TV Balun Core (dot indicates start of coil).
X3 – 20 Turns 24 SWG on TV Balun Core

Range of the circuit depends on the type of antenna used. It is very important to use matched antenna to radiate the signals effectively. I used horizontal dipole antenna, which is simple and easy to construct. For 7 MHz, ie 40 meter ham band the length of dipole antenna will be 20 meter. Use 75 Ohms co-axial cable to connect antenna and transmitter. I was able to get 57 report from station 80 kilometer away. You can easily add a Linear RF amplifier using IRF830 to get more power.

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