Circuit knowledge

Showing posts with label 4. Show all posts

Sunday, November 9, 2014

LCD Module in 4 bit Mode

The LCD module was driven directly by a microcontroller, which was on a development board for testing various programs and I/O functions. There was a switch present for turning off the enable of the display when it wasn’t being used, but this could be forgotten during some experiments. When the R/Wline of the display is permanently tied to GND (data only goes from the microcontroller to the display) then the remaining lines can safely be connected to the supply (+ve or GND). In this application however, the R/Wline was also controlled by the microcontroller. When the display is initialised correctly then nothing much should go wrong. The data sheet for the HD44780 is not very clear as to what happens with the low nibble during initialisation.

Circuit diagram :

LCD Module in 4-bit Mode Circuit Diagram

After the power-on reset the display will always be in 8-bit mode. A simple experiment (see the accompanying circuit) reveals that it is safer to use pull-down resistors to GND for the four low data lines. The data lines of the display are conﬁgured as outputs in this circuit (R/Wis high) and the ‘enable’ is toggled (which can still happen, even though it is not the intention to communicate with the display). Note that in practice the RS line will also be driven by an I/O pin, and in our circuit the R/W line as well. All data lines become high and it’s not certain if (and if so, for how long) the display can survive with four shorted data lines. The moral of the story is: in 4-bit mode you should always tie D0-D3 via resistors to ground or positive.

Friday, September 19, 2014

Simple 4 Channel Video Amplifier using NJM2582

A very simple 4 channel video amplifier electronic circuit project can be designed using NJM2582 ic suitable for video applications with SCART connector . Design of the circuit is very simple and require few external electronic parts .

Circuit diagram :

Simple 4 Channel Video Amplifier Circuit Diagram

Some features of the NJM2582 are : Operating Voltage ±5V, +5V, +11V ; 6input 4output , 2input 1output Video SW , Internal LPF , 6dB Amplifier , Internal 75Ω Driver Circuit , DC output for SCART (FUNCTION SW, BLANKING) .

Thursday, September 4, 2014

Simple LCD Module in 4 bit Mode

In many projects use is made of alphanumeric LCDs that are driven internally by Hitachi’s industry-standard HD44780 controller. These displays can be driven either in 4-bit or 8-bit mode. In the first case only the high nibble (D4 to D7) of the display’s data bus is used. The four unused connections still deserve some closer attention. The data lines can be used as either inputs or outputs for the display. It is well known that an unloaded output is ﬁne, but that a ﬂoating high-impedance input can cause problems. So what should you do with the four unused data lines when the display is used in 4-bit mode? This question arose when a schema was submitted to us where D0-D3 where tied directly to GND (the same applies if it was to +5 V) to stop the problem of ﬂoating inputs.

The LCD module was driven directly by a microcontroller, which was on a development board for testing various programs and I/O functions. There was a switch present for turning off the enable of the display when it wasn’t being used, but this could be forgotten during some experiments. When the R/Wline of the display is permanently tied to GND (data only goes from the microcontroller to the display) then the remaining lines can safely be connected to the supply (+ve or GND). In this application however, the R/Wline was also controlled by the microcontroller. When the display is initialised correctly then nothing much should go wrong. The data sheet for the HD44780 is not very clear as to what happens with the low nibble during initialisation.

After the power-on reset the display will always be in 8-bit mode. A simple experiment (see the accompanying schema) reveals that it is safer to use pull-down resistors to GND for the four low data lines. The data lines of the display are conﬁgured as outputs in this schema (R/Wis high) and the ‘enable’ is toggled (which can still happen, even though it is not the intention to communicate with the display). Note that in practice the RS line will also be driven by an I/O pin, and in our schema the R/W line as well. All data lines become high and it’s not certain if (and if so, for how long) the display can survive with four shorted data lines. The moral of the story is: in 4-bit mode you should always tie D0-D3 via resistors to ground or positive.

Author: L. Lemmens
Copyright: Elektor Electronics

Wednesday, August 27, 2014

Kicker ZX350 4 Clarity With Agressive Looks

Kickers impressive ZX350.4 amplifier.

Stillwater Designs, now better known as Kicker, is an "All American" company thats been around a long time. Back in the day, they originated the "kicker" box before anyone else even thought about it - thats probably why people still refer to them as "kicker" boxes. In the early 1990s the company started building amplifiers and has since quietly grown into a large force in the market. This time we take a look at the latest stage in the evolution of the Kicker amplifier, the ZX350.4.

Description
Kicker rates the 4-channel ZX350.4 amplifier at 60 watts per channel into 4 ohms, 90 watts into 2 ohms and 2 x 175 watts bridged into 4 ohms. The amplifier is an unregulated Class A/B design with both RCA and speaker-level inputs, and crossover and bass boost for each pair of channels. Visually, the amplifier retains its family resemblance to Kicker amps from the past several years. It has predominantly a textured black finish with a trio of rubber-capped knobs for each channel on the top plate. Swooping "V" contours in the top sheet metal frame the Kicker badge, and a red strip of silicon rubber lines the top plate on both sides.

The ZX series is an "upside-down" style amplifier. The main chassis is an aluminum extrusion that forms the bottom and sides of the amp. A cover plate made of stamped steel with the design and vents embossed in it covers the top of the amplifier. Adorning this piece are two badges (one for the logo and the other for the model number) and the control knobs for the gain, crossover and bass boost. The cover plate fits into two red silicone-rubber extrusions along each side of the heatsink. The molded plastic endcaps hold it in place.

The power/ground/remote terminal, two 20-amp fuses and the power/protect indicator light are all found on the left endcap, while the speaker connectors, RCA and hi-level inputs, fader and crossover switches are on the right endcap. Crossover frequency, gain controls and bass boost level controls are located toward the right-hand side of the cover plate.

The circuit layout inside is pretty much what youd expect from looking at the outside. The power supply and the amplification/output section each occupy half of the main board, with an empty 1" strip running right down the middle as a buffer between them. There are other ways of controlling noise from the power supply, but it looks like isolation is important to the engineers at Kicker. The preamp section is nicely contained on a daughter board suspended above the output end of the main board. Both circuit boards are double-sided, but the preamp board uses mostly surface-mount parts while the main board uses all through-hole parts.

Starting with the power supply, power and ground is accepted through two large brass blocks. These two blocks will accept up to 4-gauge cable, although the manual recommends 8-gauge for this one as it is the smallest 4-channel in the series. B+ runs through a pair of 20-amp fuses and a small inductor. It then goes past three 2,200F capacitors for primary filtering and on to two pairs of high-speed, 49-amp switching Mosfets. A TL494 pwm controller drives the switching through the toroidal transformer at about 36kHz, achieving rails of + and - 30VDC. Secondary filtering consists of four 3,300F capacitors to stabilize the rails.

Jumping over to the input section, the first thing I noticed is that the signal grounds are extremely well isolated from the chassis ground. With 40k ohms of isolation, this amplifier will never participate in any ground loops in your system - thats for sure. The signal and shield conductors from the RCA are all fed into low-noise op-amps, thus making this a differential input. This style of input will better reject noise radiated into your RCA cables. The owners manual reinforces this format by recommending twisted-pair cables rather than big fat coaxial RCAs. Differential inputs are typically found on more expensive amplifiers and have the potential for much better sound quality than less expensive designs. The gain control is accomplished through additional op-amps, rather than the cheaper (and noisier) style of attenuating the signal to ground.

Lastly, the output section consists of four complementary pairs of TIP35C/TIP36C output transistors, each capable of dissipating 125 watts, or 250 watts per output channel, which is more than adequate for this unit.

Performance
The amp performed well on the bench, meeting or exceeding every specification as listed in the owners manual. The S/N ratio was a very respectable >94dB and the frequency response measured 13Hz to an astonishing 66kHz. The crossovers drifted ever so slightly from the published spec, but the difference was small and the curves were textbook. While filters are specd at 50Hz to 200Hz, the lowpass range was measured 54Hz to 203Hz, and the highpass was 45Hz to 180Hz. The bass boost was right on with the published 18dB boost, but centered at 41Hz rather than 40Hz. Trust me, youre not going to hear the difference on any of this.

The protection circuits worked well, both short-circuit and thermal. I like that theyre self-resetting so you dont have to turn the system off and back on. On the bench the amp fired up smoothly and there was no turn-on or turn-off noise in the car at all.

Manual
The owners manual really cuts to the chase. On page 2 theres a place to write down the purchase details; then it tells you how to mount the amp. Wiring is next, still on page 2, and then it slows down a little to cover different system configurations and the setting of controls. Page 5 covers troubleshooting and specifications, while pages 6 and 7 are the warranty covered in four different languages. Speaking of warranty, Kicker provides a 2-year deal when purchased from an authorized dealer. As always, keep your receipt.

Listening
The ZX350.4 was installed in the trunk of my Buick and initially connected to the front separates and the rear 6 x 9s. The crossovers were set for fullrange and the subwoofer was not hooked up.

I started out as always with Donald Fagens Kamakiriad, which is a very well-mastered recording. There is a lot going on in all of these tracks, so it can really reveal any shortcomings with the amps and speakers. Track 1, "Trans-Island Skyway" starts out with a guitar riff, adding bass, keys and percussion as the intro builds. The bass line is pretty busy and can sound muddy, but the Kicker came through. Not only was the bass clean and clear, but everything else sounded distinct and well-balanced. The center image was a little fuzzy and quite low. I checked out "Tomorrows Girls" for the highs. The cymbals in the intro were clear and smooth. "Snowbound" revealed good low-end clarity on the Fender Rhodes keyboard and bass guitar.

Tracks from Dadas Puzzle and Mary Chapin Carpenters Come On, Come On reinforced my initial impressions that the response and clarity were excellent, but the image remained low and somewhat indistinct.

I returned to the trunk and changed the configuration. I kept the front separates connected but set the highpass to 100Hz. The other 2-channels were bridged and connected to the subwoofer with the lowpass set to the 100Hz. I repeated some earlier tracks with good results, and then went to "Posters" on the Dada CD. This one starts out with a great drum solo, adding electric guitar along the way. It sounded great, but didnt get as loud as I really like it. No foul here, its just a smaller amplifier than I have permanently installed. In this configuration it should put out 60 watts each to the front speakers, and 175 watts to the subwoofer, where I normally have 100 watts to each corner and over 300 on the subwoofer.

Conclusion
I like this amplifier a lot because it did what it said it would do. The Kicker ZX350.4 is a very straightforward unit that is usable in several configurations. When auditioning the amp in my car I didnt feel the imaging and staging were as good as my reference amps, but I realize that its not an issue for most people. However, clarity and frequency response were very impressive and thats something every consumer should be concerned with.

The ZX350.4 is stylish, somewhat aggressively so. At a retail price of $349, and a max power of 387 watts, it comes in at 90 cents per watt. As a general rule, anything with a retail price under a dollar per watt is not bad (for an amp below 500 watts). Overall its a good amp at a reasonable price.

Wednesday, August 20, 2014

4 X 15 Watt Mini Power Amplifier Wiring diagram Schematic

A lot of electronic diagram in the domain of audio amplifiers are already been published here. This schema is a little different because it is a four channel amplifier. Each channel of this amplifier can deliver an output of 15Watts into a 4 ohm speaker. The amplifier can be operated from a single 12V DC supply and this makes it possible to use this amplifier in car audio applications too.

4 X 15 Watt Mini Power Amplifier Circuit diagram :

4 X 15 Watt Mini Power Amplifier

The schema is based on the 15W BTL X 2 channel audio power amplifier IC TA8215 from Toshiba. Even though chip is specifically designed for car audio applications it can be also used for home audio applications. Two TA8215 ICs are used here in order to obtain a 4 channel amplifier system. The schema is designed almost exactly as per the application diagram in the ICs datasheet. Pins 7 and 19 are the Vcc pins of the ICs internal integrated power amplifier stages and these pins are connected to the positive supply. Pin 9 is the Vcc pin for ICs internal preamplifier and it is also connected to the positive supply. Pins 13 and 14 are the internal power amplifiers ground pins and they are tied together and connected to the ground.

The internal preamplifier’s ground pin (pin5) is connected to the common ground through a 10 Ohm resistor which makes the input ground separated from the common ground by a resistance of 10 ohms and this improves the noise rejection. The 100uF capacitor works as a power supply de-coupler. The resistor networks connected to the output lines of each amplifier improves the high frequency stability. The variable resistors (R3, R4, R12 and R13) works as the volume controller for the corresponding channels.

Notes :

Assembling the schema on a good quality PCB is a must for obtaining optimum sound quality.
Use 12V DC for powering the schema.
The ICs must be fitted with adequately sized heat sinks.
R3, R4, R12 and R13 serves as volume controllers.
K1 to K4 can be 4 Ohm, 20W speakers.
This amplifier schema can be used in a variety of applications such as car audio systems, home theater systems, personal audio systems, public address systems etc.

Wednesday, August 13, 2014

Burglar Alarm with 4 ways

In this schema, the alarm will be switched on under the following four different conditions: 1. When light falls on LDR1 (at the entry to the premises). 2. When light falling on LDR2 is obstructed. 3. When door switches are opened or a wire is broken. 4. When a handle is touched.

http://www.electronic-diagram-diagrams.com/alarmsimages/10.gif

The light dependent resistor LDR1 should be placed in darkness near the door lock or handle etc. If an intruder flashes his torch, its light will fall on LDR1, reducing the voltage drop across it and so also the voltage applied to trigger 1 (pin 6) of IC1. Thus transistor T2 will get forward biased and relay RL1 energise and operate the alarm. Sensitivity of LDR1 can be adjusted by varying preset VR1. LDR2 may be placed on one side of a corridor such that the beam of light from a light source always falls on it. When an intruder passes through the corridor, his shadow falls on LDR2. As a result voltage drop across LDR2 increases and pin 8 of IC1 goes low while output pin 9 of IC1 goes high. Transistor T2 gets switched on and the relay operates to set the alarm. The sensitivity of LDR2 can be adjusted by varying potentiometer VR2. A long but very thin wire may be connected between the points A and B or C and D across a window or a door. This long wire may even be used to lock or tie something. If anyone cuts or breaks this wire, the alarm will be switched on as pin 8 or 6 will go low. In place of the wire between points A and B or C and D door switches can be connected. These switches should be fixed on the door in such a way that when the door is closed the switch gets closed and when the door is open the switch remains open. If the switches or wire, are not used between these points, the points should be shorted. With the help of a wire, connect the touch point (P) with the handle of a door or some other suitable object made of conducting material. When one touches this handle or the other connected object, pin 6 of IC1 goes ‘low’. So the alarm and the relay gets switched on. Remember that the object connected to this touch point should be well insulated from ground. For good touch action, potentiometer VR3 should be properly adjusted. If potentiometer VR3 tapping is held more towards ground, the alarm will get switched on even without touching. In such a situation, the tapping should be raised. But the tapping point should not be raised too much as the touch action would then vanish. When you vary potentiometer VR1, re-adjust the sensitivity of the touch point with the help of potentiometer VR3 properly. If the alarm has a voltage rating of other than 6V (more than 6V), or if it draws a high current (more than 150 mA), connect it through the relay points as shown by the dotted lines. As a burglar alarm, battery backup is necessary for this schema. Note: Electric sparking in the vicinity of this schema may cause false triggering of the schema. To avoid this adjust potentiometer VR3 properly.