my transmitter needs a BIGger BOOST!

[mstechca]

:lol:

This is very interesting. I had and still have the nerve to take my superregen detector and swap the output with the input, and have no amplifiers or other circuits whatsoever attached. When I apply the battery voltage, and the transmitter and receiver are close to each other, and both detectors use the exact same components in the exact same configuration, my signal goes across well, but I would like more of a boost, even if the battery voltage is low (about 3V).

I will provide a circuit when I get a chance.

Is there a way I can calculate the maximum distance my transmitter can transmit a clear signal given the current and the voltage at the antenna?

and it seems that this transmitter of mine is the most stable one I have built.

 

[audioguru]

A single transistor transmitter is about 50% efficient, so half the supplied battery power is transmitted and the other half heats the circuit.

You can't determine range unless the receiver's sensitivity is calibrated.

 

[stevez]

I think the statement "you can't determine the range ..." applies here but there are some things worth mentioning. It is possible to measure or model the performance of a transmitter system - and as already implied, the performance of the receiving system can also be known. By 'system' I mean everything from the mic to the antenna including the surrounding environment. Path losses for line of sight are known (maybe quite variable but known) and beyond line of sight things are still well understood - enough so that some relative predictions can be made. All of this takes a lot of work, resources, skill, etc - which is why I would agree with the "you can't determine the range.." statement for this situation.

 

[stevez]

Another thought - many amateur radio operators attempt to make contact with the least amount of power over the longest distance. They do this on many frequencies - the activity is generally known as QRP. You might find some helpful information from QRP groups. That group also attracts people who try to do the most with the least in terms of equipment and systems complexity and there are probably some who have worked hard on regen equipment.

QRP comes from a list of "Q" signals that were used back in the days of CW or morse code. QRP refers to decrease in power. QSB refers to fading. QTH refers to location. There are many more. Numbers were also used - '73' being a popular carry over which generally means "best wishes" or something like that. Healthtech probably cares about this - at least I hope so.

 

[audioguru]

Hi Steve,
MStechca is going to have a very difficult time measuring the range of his radio transmitter and receiver system because his low battery voltage (about 3V) is QSB and probably started its life long ago as a 9V battery.
His battery's impedance is probably so high now that it is his transmitter's modulator. He shouts near it and its case vibrations modulate its fading output voltage.

The radio transmitter and receiver are actually super-regen single transistor circuits, you know. They both have their regen oscillation out of control and are producing continuous oscillation. Maybe having a multi-element yagi directional antenna on each one will extend their range to more than a few cm. :lol:

 

[mstechca]

I mention 3V because I wanted to make a transmitter that works on a 9V battery that is at least 1/3 alive.

I have 2 batteries labelled 9V right now. One measures at 5.5V and the other at around 7.5V.

I tried 2 scenarios. The 1st one is the push-pull amplifier connected through a coupling capacitor to the regen detector. Results: very poor, I'll be lucky if a signal goes across when the transmitter is touching the receiver.

The 2nd case is the same as the first, but I removed the capacitor and replaced it with a wire (a short). Results: better, but the signal is distorted. Any kind of disconnection in my circuit results in local interference to neighbouring stations on my receiver.

I need to know some ways to remove the distortion.

I still didn't have the time yet to make the circuit.

 

[bryan1]

Hiya Mstechca,
I remember an aricle in siliconchip where Stan Swan palys around with the picaxe chips and wifi etc. In one of the articles he setup a crude way of measuring range using a multimeter and a couple of germanian diodes. I'll have a look for the article later if I get a chance but it's really worth taking a look what Stan has achieved using a simple picaxe and transmitting it over a huge range.

Just a Thought Bryan

 

[mstechca]

get rid of this post only. I hit the wrong button. See the next post please.

 

[mstechca]

I posted my detector.

I tried to connect a generic push-pull amplifier to point B and the antenna to point A. The only way I got a result was when the amplifier was directly connected to B, probably because two resistors 27K and 6K (in my push-pull amplifier) are in parallel.

Is there a better way I can make an FM transmitter using the circuit shown?

The turquoise capacitor I think determines the quench frequency.

The three yellow components determine frequency or at least help determine frequency.

 

[audioguru]

I mention 3V because I wanted to make a transmitter that works on a 9V battery that is at least 1/3 alive.

I have 2 batteries labelled 9V right now. One measures at 5.5V and the other at around 7.5V.

I thought so.
Didn't you know that a little 9V battery is considered to be dead when its voltage measures 6V or less with a 1k ohm load?
Because its internal resistance rises to such a high value that its voltage changes too much when the circuit's current changes.

It is difficult to design a circuit that functions well when its supply voltage changes from 9V to 6V.
It is nearly impossible to have a circuit operate well when its supply voltage changes from 9V to 3V.

 

[audioguru]

I posted my detector.
Is there a better way I can make an FM transmitter using the circuit shown?

Like i said before, you have a high impedance tank in a low impedance emitter, squashing the tuning ability of the tank. The tank should be the collector load.
If it oscillates, the frequency will not be the tuned frequency of the tank, because a transistor needs a low impedance at its emitter in order to have gain. Its collector inductor isn't tuned so it could oscillate at any other frequency.
The circuit doesn't have any way to quench. The 140pF capacitor only loads-down the collector.
It doesn't have an FM detector nor an AM detector so why connect it to an audio amplifier?

 

[Nigel Goodwin]

As we've been saying for months, your random circuit changes (with no idea of what you're doing!), have produced a circuit which ISN'T a super regen, and isn't likely to work anywhere near as well as they do (which isn't well anyway!), if it works at all.

Why don't you just build the super regen as the original circuit?, your changes have continually made it worse!.

 

[audioguru]

Here's an article that explains in detail how a super-regen works.
It has the usual self-quenching circuit, plus some interesting new ones.
**broken link removed**

 

[mstechca]

this configuration works for me as a super regen receiver, and some receivers can be transmitters.

 

[audioguru]

Bop! :lol: :lol: :lol: :lol:

 

[Nigel Goodwin]

this configuration works for me as a super regen receiver, and some receivers can be transmitters.

If it works why are you still asking questions?.

 

[mstechca]

because I want to make a super regen transmitter using the same values as my super regen receiver, and the transmitter doesn't work well enough.

 

[audioguru]

You might have the correct values for the parts in your super-regen receiver and transmitter, but they are in the wrong places for the transistors to work properly.

 

[Nigel Goodwin]

because I want to make a super regen transmitter using the same values as my super regen receiver, and the transmitter doesn't work well enough.

Fairly obviously you can't have a super regen transmitter!, a transmitter needs to oscillate permanently - a super regen merely 'hovers' on the edge of oscillation.

But neither are super regen circuits anyway!.