lanre

pls, I've seriously been battling with d "4+0 Link Internal Intercom"design. I don't know if anyone has constructed it also to noty me of any modification. I couldn't get MC145436, I'm using MT8870C in place. Also, I dont know if IC3 should be CD4514 or CD4515 (as the latter has low output on select). Also, I'm not sure if the series R9/R10 combination junction should be connected to d IC2 (CD145436) input pin and if so, what is the essence of this sinve we don't want dc signal to get to the input? I'll like to know further which of the capacitors :C1 - C4 is ceramic/ electrolytic? thanks

pls, I wish to design a 30Vdc 500mA for my Printer. Pls help with all deatials. Also, pls does a crysta oscillator have a polarity?

thanks for ur usual assistance on my project:"4 Link Intercom" at http://www.electronics-lab.com/projects/telephone/015/index.html. Pls, I want to confirm d following: a.) Is there any common connection between the two resistors labelled R9, R10 and the capacitor C4 at the DTMF input (I mean, are they connected at the point where the C4 input crosses the series R9/R10 combination)? b.) Pin 8 of IC2(DTMF decoder) and Pin12 of IC3 are supposed to be grounded, but they're both connected to RS flip-flop, will that still work becos Only Pin 23 of IC3 which sholud be at logic 0 is grounded? c.) Can I use a D-fli-flop with D-terminal connected to logic 0 (zero volt) in place of an RS flipflop since the only terminals I need are the R,S & Q in the diagram? d.) Does the audio amplifier has an alternative such as using an inductor instead of it and if so how do I go about the connection to realise the same result for the above project? Pls, help me out, am about concluding the project and I'll be very happy if it works!

Pls, I need information about where to get an audio transformer wth 1k/8R centre-tapped at IK wnding and the following ICs: MC 45436 DTMF Decoder CD 4515B 1 of 16 decoder CD 4013B dual RS flip flop Pls, I want a place where small quantity supply order can be placed. lanre Nigeria

Hi, Pls, I urgently need the datasheet as well as possible place to get these ICs (or thier equvalents) required to carry out the project below http://www.electronics-lab.com/projects/telephone/015/index.html MC 45436 DTMF Decoder CD 4515B 1 of 16 decoder CD 4013B Dual RS flip flop I also need a possible place to get an audio transformer (1K/8R centre-tapped at 1Kwinding) Pls, the components are really disturbing the progress of my project. The components are specified in the address below: http://www.electronics-lab.com/projects/telephone/014/index.html

Pls, the ICs (MC45436 DTMF decoder, CD 4515B 1x16 decoder and CD4013B RS flip flop) required for the above project are just too scarce. I searched the web and even for the datasheets and possible replacement all to no avail. The replacemnts gotten from the market didn't satisfy me with their descriptions. I got CD4543BE (Cmos BCD-to-& segment latch decoder for LCD) in place of MC45436-which I was informed has a wrong specification, CD4515BE(cmos 4-bit latch/4-to-16 line decoder with output low on select) in place of CD4515B. Pls help me out in any form as am really feeling sad about the current development. My project is at stake. Lanre :(

Concerning the schematic of the above project which I intend doing, am still havng some problems: Is there any alternative to the audio transformer (impedance-matching xformer)used in the project? And is ther any common equipmnt where I can see a sample to remove it from the scrap? Is that specification (1k/8R centre tappd at 1K) compulsory or any type will work? Am really having problem getting it here in Nigeria. Is the specification IC2 wth no MC45436 correct because I was only able to get MC4543? Must CD 4013 be a dual RS flip-flop or can it be D-flip-flop? Will CD4515B but 4 to 16 decoder also go for the IC3 in place of 1 to 16? Can I also connect more than 4 phones to the free legs of the IC3?