Selasa, 27 September 2011

Senin, 26 September 2011

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Modif Tuner FM Sebagai Oscilator Pemancar


Oscilator merupakan bagian terpenting dalam perakitan pemancar. bisa menggunakan oscilator colpits atau yang lain.

modifikasi oscilator biasa menggunakan varicap dioda untuk memindah frekuensi. hal ini dalam perakitannya akan banyak menemui kesulitan karena kurang stabilnya regulator power supply untuk oscilator.

dalam perkembangannya teknik ini juga biasa dipakai untuk teknik Phase looked loop (PLL) yang sudah jelas lebih stabil frekuensinya.

Coba kita bahas.

Tuner Fm ini sejatinya adalah untuk receiver/penerima radio FM. dimana disitu terdapat oscilator, rf amplifier dan mixer…. dimana ada pinout untuk ground, tegangan +, if output, rf output untuk di counter, dan AGC. masing-masing kaki memiliki fungsi yang berbeda-beda. (lihat gambar)

ok dari situ kita gunakan bagian oscilatornya saja.

jadi kita gunakan hanya kaki ground, tegangan (+5 volt saja atau diberi IC LM7805), lalu rf output untuk counter frekuensi dapat langsung disambungkan ke bagian buffer pemancar. lalu untuk audio input dihubungkan dengan AGC pinout tuner.

untuk kestabilan coba pasang resistor 100KΩ dari kaki AGC ke tegangan +.

bsekrup body tuner dengan boxnya dengan kuat. coba berikan input audio dari pre amp. kalo mau mencoba didengarkan di radio. coba posisikan tuner ke bagian paling bawah (sekitar 88MHz). lalu coba dengarkan pada 99,5 MHz. karena selisih pemancar 10,7 MHz. kalo sudah berarti sudah bisa diteruskan ke bagian buffer, driver, dan final pemancar.

hal ini menurut prakteknya didapatkan kestabilan yang lumayan, mendekati oscilator sistem PLL. bisa juga untuk masuk pada repeter 2meter band.

selamat mencoba

Rabu, 21 September 2011

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Oscilator Dengan Ic Max2606

modulator FM88-108mhz



This is a FM transmitter circuit using Maxim semiconductors IC MAX2606. In the circuit the nominal frequency is set to 100 Mhz by inductor L1, (390nH) . The left and right channel audio signals from your source are added by R3 and R4, and attenuated by the POT R2. R2 can be used as a volume control .POT R1 can be used to select a channel of transmission between 88Mhz and 108Mhz.Use 80 cm long wire as the antena.

Skema Rangkaian Pemancar Fm 88-108Mhz



Note:
* Use a battery for powering the circuit.It will reduce noise.
* An FM antenna from a old radio is a better option than the wire antenna.


IC MAX2606 Description

The MAX2605-MAX2609 are compact, high-performance intermediate-frequency (IF) voltage-controlled oscillators (VCOs) designed specifically for demanding portable wireless communication systems. They combine monolithic construction with low-noise, low-power operation in a tiny 6-pin SOT23 package.

These low-noise VCOs feature an on-chip varactor and feedback capacitors that eliminate the need for external tuning elements, making the MAX2605-MAX2609 ideal for portable systems. Only an external inductor is required to set the oscillation frequency. In addition, an integrated differential output buffer is provided for driving a mixer or prescaler. The buffer output is capable of supplying up to -8dBm (differential) with a simple power match. It also provides isolation from load impedance variations.

The MAX2605-MAX2609 operate from a single +2.7V to +5.5V supply and offer low current consumption. These IF oscillators can cover the 45MHz to 650MHz frequency range.



IC MAX2606 Absolute Maximum Rating
VCC to GND..............................................................-0.3V to +6V
IND to GND ................................................-0.6V to (VCC + 0.3V)
TUNE to GND .............................................-0.3V to (VCC + 0.3V)
OUT+, OUT- to GND ..................................-0.3V to (VCC + 0.6V)
Continuous Power Dissipation (TA = +85°C)
6-Pin SOT23 (derate 8.7mW/°C above +70°C)...........696mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
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Skema Runing Led Simple

Circuit of Led runs, led can be seen using, as an indicator while ic IC4017 is that it functions as a counter with the help of a clock generated by a 555 timer ic, slow movement which quickly led the flames quickly depending on the clock late in the output by the timer IC.




Skema Rangkaian Led Berjalan

List of Components used:
IC 4017
IC Ne 555
Led
R 4.7K
R 1K
VR 100K
C 10mf/16V
C 100nf
To change the mode from the line led to the form of a text can be done with the sort led to the form of the text that will vary in, just what you want when you led or will be up on a path or line of IC 4017 should be adding a series of brace.
series brace can use here or NPN transistors can also use the relay if the load would be greater

Selasa, 20 September 2011

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Logic overvoltage protection


The Logic overvoltage protection circuit is designed to protect the TTL logic ICs with supply voltages of 5 V from overvoltage conditions.

How it work :
Zener diode ZD1 senses the power supply voltage, and if the supply voltage rise above 6 V, Q1 will-turn on. Therefore, Q2 conducts short the rail. Next events depend on the source supply. It will either shut down, go into current-limit or blow its supply fuse. None of these will damage the TTL chips. The rating of Q2 depends on the source supply, and whether it will be required to operate continuously in the event of failure. Its current rating has to be in excess of the source supply.

Logic overvoltage protection Parts list :
R1 : 330 ohm
R2 : 47 ohm
R3 : 1K
R4 : 220 ohm
Q1 : BC 107, 2N3704
Q2 : BD132
Q3 : Bc478, 2N3702
Led
Zd1 : 6 V

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