Trouble with Audioguru's FM Transmitter circuit

[t_anjan]

How many attachments is one user allowed to make?

 

[audioguru]

I was cutoff at 200MB.

 

[t_anjan]

I have made only 16 posts, 200 MB is still a long way off. But I still can't make any attachments.

 

[Nigel Goodwin]

I have made only 16 posts, 200 MB is still a long way off. But I still can't make any attachments.

What are you trying to attach?, and how big is it? - there are restrictions on both file types and file sizes.

 

[t_anjan]

For the past 3 days I have been trying to attach 2 jpeg files. It kept asking me to contact the board administrator as I had reached the max limit for attachments. But that was before the topic moved to the second page.
But now I tried to attach the same files and it worked. Could it be because one user can attach only a set number of KB per page?

Anyway I have attached the photo of a new Inductor that I coiled using the enamelled wire from a coax cable.
I've also attached the photo of the electret mic and antenna.

The photos of the electret mics I saw on the net have a metallic top. But mine has some kind of black coloured furry top. How do I check if it is working?

 

[panic mode]

if the wire is really from coax cable it is definitelly not enameled
and it looks like bare copper wire - not enameled.

why is it 9-turn coil? for broadcast fm range circuit like this
it should be only 4 or 5 turns wound on 5-6mm form which is then
removed.

 

[audioguru]

Hi T_an,
Where did you find that 250V candy-striped old cap? Its inductance is probably more than your inductor!

Hi Panic Mode,
My FM transmitter works fine with a 9-turn closely wound coil made from 1mm enamelled wire on a 3mm former, and also this project from where I got the idea:
**broken link removed**

 

[audioguru]

Here is a pic of my FM transmitter circuit built on a copy of Veroboard. It is Mod4, but using the circuit board of Mod3, so a few of its parts are very close together and I have resistor R6 and little ceramic cap C2 underneath. I have a 680 ohm resistor at the lower left as a current-limiting resistor for its LED. I don't have any space on this board for the 5.1V zener diode in series with the LED that shuts it off when the batt gets down to about 5.3V as a low-batt warning.

Look at the tiny size of its trimcaps and electret mic. The mic has a thick rubber sleeve around it so is actually much smaller. The 1mm wire for my coils is so stiff that you can stand on them and they don't change. :lol:

 

[Dr.EM]

Now thats a neat layout!

That stuff looks better than actual veroboard, with the little white stripes on the top, makes it easier to see what goes where.

 

[audioguru]

Hi Dr. EM,
Thanks, I make all my prototypes like that. :lol:
I used to use real Veroboard that was epoxy-fiberglass and was a dark blue. It was hard to see. Then I couldn't buy it anymore over here (Canada) so I used an excellent Chinese copy for about 10 years. My supplier stopped importing it (maybe I was the only purchaser) so I found this one. It's not fiberglass like the others so it might warp and it seems to be brittle. I don't know what it is made from but it stinks!
Maybe made from dung (yuck!) or something.

I have made many of my high-impedance chaser projects with it and I took a few to my daughter's house. One didn't work properly there and I thought it got zapped by static on the way over there. After about 1 week the condensation (it was very cold out that day) dried and it began to work properly. :lol:

 

[Dr.EM]

Condensation, never knew that could cause trouble, perhaps thats why the old in-car clock stopped working.

I think i'm using the real Vero stuff, its pretty tough, no stripes (unfortunately) and its that brownish colour. Has the "new electrical device" smell :lol: . Fairly sure it's not made of dung though :lol:

How do you put your projects together? At the moment, i'm sort of placing each component, cut leads and solder. What I plan to try today is selotaping every component on first, cutting all the leads and doing all the soldering at once. I hope this would be faster, and I wouldn't get solder drying on the bit, which means I won't have to keep wiping it.

 

[Nigel Goodwin]

How do you put your projects together? At the moment, i'm sort of placing each component, cut leads and solder. What I plan to try today is selotaping every component on first, cutting all the leads and doing all the soldering at once. I hope this would be faster, and I wouldn't get solder drying on the bit, which means I won't have to keep wiping it.

I fit the component, solder it, then cut the leads - I don't think trying to tape multiple components down would be very effective?.

 

[Dr.EM]

I tried it this afternnon, with the octave up effect. I simply made a copy of the version on the breadboard on veroboard, stuck all the components down with tape, then took it to be soldered. It was definately the quickest soldering i've ever done, and i'll probably use that technique for any more suitable projects in the future. There would be times when it would be unsuitable, but for most the types of project I do, it seems effective.

 

[audioguru]

Hi,
I use very sticky green painter's masking tape to hold down many jumpers at the same time, cut their wires then solder.
I also tape a few resistos at a time, cut the wires then solder.
ICs, transistors and capacitors are held with my fingers, cut the wires then solder.
Very fast.

Isn't it interesting that everyone does it differently? 8)

 

[audioguru]

Hi Dr. EM,
I just finished for now at your "My music is here" site and wow, I am really impressed! Thanks. :lol: :lol:
I have most of my new computer's hard drive to fill with music.

My son buys fairly new computers on E-bay, cleans them and re-sells them. It started as upgrades for him but now has become very profitable.
About a month ago he bought a laptop that belonged to a DJ. It was packed with all kinds of music from oldies up to now. I got it all. Lots of fun! :lol:

 

[Dr.EM]

It is interesting how people have thier own methods, usually just different orders to how things are done.

Cheers for checking that out , that site has a whole host of unsigned electronic music.

That laptop sounds great, even if it were just for the music! Bet you got loads of great stuff on there.

 

[zachtheterrible]

wow, this topic kind of took off without me even realizing :lol:

my 2 cents worth: I put in my componenents, solder, and then cut the leads. The way I figure, is that maybe the long lead acts as sort of a heatsink. or maybe it barely does anything :roll:

 

[Dr.EM]

Hmm, good point. I always just find it easier to solder with extremely short leads, but with diodes and transistors, it may be worth leaving them long. What I tend to do with them currently is mount them some distance from the board. Another tip is to clip a crocodile clip onto the leads above the board, again, as a heatsink.

 

[audioguru]

Hi Dr. EM,
If you mount diodes and transistors some distance from the board then the inductance and stray capacitance of the wires might disrupt the circuit at VHF frequencies. I don't need to bother with long wires or heatsinks for them when soldering since my iron is temp-controlled. It is the fixed-temp kind, about 38 years old, and its temp is chosen by the slug manufactured into its replaceable tip which also seems to last forever.
These soldering irons are still manufactured today. :lol:

 

[Nigel Goodwin]

Hi Dr. EM,
If you mount diodes and transistors some distance from the board then the inductance and stray capacitance of the wires might disrupt the circuit at VHF frequencies. I don't need to bother with long wires or heatsinks for them when soldering since my iron is temp-controlled. It is the fixed-temp kind, about 38 years old, and its temp is chosen by the slug manufactured into its replaceable tip which also seems to last forever.
These soldering irons are still manufactured today. :lol:

Even a slight amount of soldering skill prevents any heat damage, there's no need for temperature controlled irons to do so - although they are nice to have, but for other reasons, not thermal damage. Just solder the joint quickly and cleanly, there's no need for heatshunts or anything else, there should be no time for heat to travel enough to cause damage.

I've never really liked the Weller irons, I've always used Antex ones, my current ones are temperature controlled, with the controller in the handle.