Transmitter question

[zachtheterrible]

have u built it vaibhav birit?

 

[Vaibhav Birit]

Currently, i am in that process of building it. I am searching for the MPF102 transistor which is the all imp. transistor.

But i can tell you for sure that it works. There are several people who have made it. You can go through the authors web pages and find several 'Maiden Voyages of RSS' .Its very easy to make.

I am doing the same. Only let me find the MPF102.

 

[audioguru]

Hi,
The Radio Shack Special project doesn't have any spec's, maybe it just picks-up strong local stations. It might not pick-up Zach's flea-power transmitter very far away.
For a super-regen receiver to have high gain, its positive feedback reduces its bandwidth. Zach's FM broadcast band receiver must have both a high gain and a wide bandwidth.
Maybe the $5 Wal-Mart radio that some of its parts come from is better, and might even use a newer Philips IC.

Philips has 2 newer FM radio IC's than the old TDA7000, but they are both tiny surface-mount ICs. I don't know if they still make the TDA7000 since their javascript messes-up my computer. Go to
www.philipssemiconductors.com and look at audio.

 

[zachtheterrible]

thx. i looked that up and found three different kinds of FM receiver IC's. Here is the link **broken link removed**. Which one should i use? And since they are not the original TDA7000, am I going to have to make changes to the other components? Thx

 

[mstechca]

Take a look
**broken link removed**

Build only the last stage of the circuit (everything to the right of C2). Now add a decent audio source and connect it to C2 and ground.

It works for me. I changed the 4.7pF capacitor to 15pF for better results. I removed R7 because it lowers the current level and the range is decreased.[/img]

 

[audioguru]

Hi Zach,
Search on Google and you'll find 2720 articles about Philips' TDA7000, including the new ones that are surface-mount only.
Get the datasheets from Philips' site or also from Google, they have schematics, parts lists and PCB layouts.
Have you built anything with surface-mount ICs? They are really tiny and most do-it-yourself'ers stay away from them.

And here's another FM transmitter toy. Don't most circuits use the same oscillator? Except this one that has the very important emitter resistor of its oscillator removed.

 

[zachtheterrible]

I built that very same circuit and had the same problem that i am having with this one: range. I think thats why i need to build this receiver. Where can I get these TDA7000 or 7010's? Ive searched ALL over the internet and havent come up with anything. You can order directly from philips but u have to order a minimum of 1000 :lol: . As for buying the kit, i'd kind of like to make this thing myself

 

[John Sorensen]

Here's what's in the $5 Wal Mart radio

I cracked open my $5 Wal-Mart radio last night. It uses a CD7613. I tried doing a search for it, and found only that it is a single chip AM-FM radio (duh). Couldn't find a datasheet. The radio is a goldmine for DIY radio parts, most of which I don't even recognize, but it's not like most of the radios you see now-adays with one IC and a bunch of microscopic SMT.

Speaking of SMT

Have you built anything with surface-mount ICs? They are really tiny and most do-it-yourself'ers stay away from them.

I used to be anti-SMT but I dabbled more and more and now all my designs are all SMT (I'm just an opinionated hobbiest). I buy double sided copper clad boards, and trace my design onto them using carbon paper. Then I cut the traces using a Dremel. I use SOIC, SOT-23, and 1206 sized parts with good results. The best part is with a careful layout I get a solid groundplane and the performance of my circuits has been noticably better.

This works fine with small to medium sized projects. For the big ones, or ones that use finer pitched ICs, I have ExpressPCB make them.

In summary, if you're on the fence about using SMT, DO IT! I'm all-SMT all-day.

j.

 

[zachtheterrible]

Ive never done my own pcb, lol. I just stick w/ good ol' veroboard. Works great for all of my projects. :lol:

I ordered 3 TDA7000's on the net the other day and expect 2 get 'em in the mail 2day

 

[John Sorensen]

Well, you might want to consider it for this project! Like I said, a solid ground plane makes real differences. I even make my through hole components into SMT if I have to use them. Like this ICL8038 project I just did, apparently it's obsolete so I had to use a DIP package. So I either use a socket and bend the socket's pins out, or (for more disposable chips), I bend the pins under (into a kind of J-lead) so I can surface mount them.

j.

 

[zachtheterrible]

yeah . . . maybe one of these days . . .

 

[Optikon]

Re: Here's what's in the $5 Wal Mart radio

I cracked open my $5 Wal-Mart radio last night. It uses a CD7613. I tried doing a search for it, and found only that it is a single chip AM-FM radio (duh). Couldn't find a datasheet. The radio is a goldmine for DIY radio parts, most of which I don't even recognize, but it's not like most of the radios you see now-adays with one IC and a bunch of microscopic SMT.

Speaking of SMT

Have you built anything with surface-mount ICs? They are really tiny and most do-it-yourself'ers stay away from them.

I used to be anti-SMT but I dabbled more and more and now all my designs are all SMT (I'm just an opinionated hobbiest). I buy double sided copper clad boards, and trace my design onto them using carbon paper. Then I cut the traces using a Dremel. I use SOIC, SOT-23, and 1206 sized parts with good results. The best part is with a careful layout I get a solid groundplane and the performance of my circuits has been noticably better.

This works fine with small to medium sized projects. For the big ones, or ones that use finer pitched ICs, I have ExpressPCB make them.

In summary, if you're on the fence about using SMT, DO IT! I'm all-SMT all-day.

j.

I agree.. for analog designs / high speed (high freq) designs I use just a piece of copper board. I drill out traces or just "skywire" with small short pieces of wire-wrap wire (~30 ga). Works well and good ground planes are invaluable when doing anything that is high speed.

I also use all surface mount and would never go back. You just can't beat the small parasitics of the packages. Some of the parts these days are getting so small.. have you seen the "leadless" types like QFN etc..? what about SOT-563 and SOT-523? Ever tried a small(6 pin) BGA by hand? These things really should be handled by a machine.. but with alot of patience and a few soldering miracles, it can be done!

 

[John Sorensen]

Some of the parts these days are getting so small.. have you seen the "leadless" types like QFN etc..? what about SOT-563 and SOT-523? Ever tried a small(6 pin) BGA by hand?

Haven't "had to" yet :wink:

I've used some smaller parts, but I prefer the larger ones because I can cut traces that run under them. It takes a steeady hand. One day I'll post some pics.

j.

 

[AMPdeck]

there is no coil to filter out the harmonics. I made the circuit meself. Here it is. I get static ALL over the dial though, but havent found the base frequency yet, wudup wit that?

hello zach....what software youre using to draw that schematic...?

 

[zachtheterrible]

i found out the static all over the dial was cuz i was 2 close 2 the receiver . i didnt draw the schematic, it was on the net.