Need Help Finding Part for RF Transistor / Oscillator - Page 1
Forum section: electronics / beginners

author: Mechatrommer
author_rank: Super Contributor
timestamp: January 30, 2011, 07:19:36 pm
content: hi, i need to know where can i get part in the picture below,or equivalent. from research, its somesort of 433MHz rf transistor and it is used in my Cheapo chinese RF Transmiter module. I've done searching in ebay and google with no success. Location can be from anywhere, hopefully available shipping to Malaysia. Thanx in advance.Regards,Shafri.

author: Zero999
author_rank: Super Contributor
timestamp: January 30, 2011, 07:37:29 pm
content: It's not a transistor.It's either a SAW resonator or an oscillator IC, how many pins does it have?

author: Mechatrommer
author_rank: Super Contributor
timestamp: January 31, 2011, 11:13:52 am
content: 3 pins. its the main drive in the RF transmitter i think, the other components just plain smd transistors, caps and diodes.edit: this is the whole circuit.yellow wire tap = serial out from mcu to RF circuit.big red wire and pcb strip (left bottom) is the RF antenna.rightmost top chip is a unknown mcu, but dont bother.the RF circuit is just a quarter area from the whole PCB (bottom), the rest is digital and supporting analog (v.reg etc).

author: Psi
author_rank: Super Contributor
timestamp: January 31, 2011, 12:03:41 pm
content: here is a datasheet of something very similarhttp://www.alldatasheet.com/datasheet-pdf/pdf/232413/ACT/ACTR433A/433.92/TO39-1.5.html

author: tyblu
author_rank: Frequent Contributor
timestamp: February 01, 2011, 02:16:45 am
content: The SOT23 part is probably the driver transistor.

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 01, 2011, 03:52:53 am
content: Taken from datasheet linked by Psi. here is the diagram application for ACTR433, i think my Cheapo Tx is a variation of this, the transistor maybe driving the SAW device (on-off by serial out digital hi-lo), but i meant, the SAW device is the modulator (mixing digital data with carrier signal at 433MHz), that send the modulated "digital data" out of air (through antenna). I'm not an RF expert myself, but just imagining.

author: radiocrazier
author_rank: Contributor
timestamp: February 01, 2011, 05:48:38 am
content: I'm a chinese student, you try :GWR433A, it is a SAW resonator anything I could help you?you bought 433 module I could buy it every electronic market, very easy to success, Mechatrommer is right too. If you can't find this component,you can just find any resonators only 433MHz, but it can oscllating 433MHz when the transistor base in High electronic level.

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 01, 2011, 04:07:15 pm
content: Quote from: radiocrazier on February 01, 2011, 05:48:38 amjust in time James! i bought this module from a chinese seller, chinese selling alot of this cheapo stuffs, good value. but i need the resonator alone, as i will buying parts separately and soldered together on pcb. finding in the internet of the exact part number is no success. can you find me supplier for this resonator? or can you be the supplier as well?ps: my other option will be to buy bulk of this module, and desolder each components to be placed in new pcb, but i think that will take lot of works (thinking reflow right now). buying the complete module is still on the cheap side for my project. i'm just looking the possibility of even cheaper, and as i already stated, to be placed on different pcb.

author: Zero999
author_rank: Super Contributor
timestamp: February 01, 2011, 06:27:10 pm
content: What sort of modulation is it supposed to give you? AM/FM?It looks like it will do both simultaneously and the frequency will probably drift as the power supply changes.

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 02, 2011, 02:15:20 am
content: i strongly believe its AM (ASK), and from the datasheet given this resonator can drift very little ±75 kHz from its center frequency 433.92MHz (433.845 min, 433.995 max) with Vsupply ±30VDC. Here is another one sold as module (smaller)http://www.made-in-china.com/showroom/jmrtech/product-detailDoUntLGjOIhV/China-Ask-Am-Transmitter-Module-TX1-.html

author: radiocrazier
author_rank: Contributor
timestamp: February 02, 2011, 11:17:54 am
content: Mechatrommerm, are you in china now?, what province are you in? I study in Sichuan Chengdu,and there is a great electronic components market,maybe this resonator very cheap 6.00RMB/10pce 433.92MHz BX R433A.But I will help you to ask the supplies and translate the language.i have not bought the resonator like 433. so sorry for my less of 433 SAW resonator experiments

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 02, 2011, 03:52:45 pm
content: Quote from: radiocrazier on February 02, 2011, 11:17:54 amI am from Malaysia, its hard to find electronics components here. Thanx for your help, i appreciate it, but i hope it will not trouble you too much.

author: radiocrazier
author_rank: Contributor
timestamp: February 03, 2011, 10:18:16 am
content: Quote from: Mechatrommer on February 02, 2011, 03:52:45 pmOh it dosen't matter,It's my pleasure,I like making components and searching the Data for it, but you are nit in china,I feel very sorry I couldn't help you so much