Shoe Box Radio Upgrade, cool ideas wanted

[Space Varmint]

The base of a transistor has a medium impedance. They don't match the low impedance of the antenna on a radio.

Well, if the impedance in too high, at least around here, I pick up unwanted noise. Not sure what it is but sounds like the old analog TV carrier with blank pulse and all that. You know, like a buzzing sound. I've heard it on every radio I've ever made, any type until I lower that impedance. In fact I am changing the JFET front end to go to something lower like a BJT.

 

[Space Varmint]

Well my power is back on so I can go to work. Don't now what happened but a neighbor said there was something going on with traffic on the road.

 

[Space Varmint]

Regenerative and superregenerative receivers are two totally different breeds.

You know, I thought you had said superhet at first. So if you know something....spill it!

 

[Space Varmint]

OK, now you guys got me all excited! Did somebody say radio? Hell, I'll take a radio over a girl any day. Guess I finally reached that age ....Oh well.

Now getting back to that radio... Audioguru, I still want this thing to operate on nothing (power). So I'm gonna leave out the AGC. I've been tinkering and found out with the bandwidth I've got right now which isn't a whole hell of allot, that I could just throw a compensation network in it to even it out. So it looks like this thing is pretty dependent upon the tuning network which is also the fromt end filter the way it works out. But they are fun! You guys should try this. All you do is make an rf amp and make them CE (Common Emitter) amps. So make an rf front end (amp) then make another CE amp so that it's collector output will be in phase with the antenna input. Then take a capacitor and a variable resistor (is how I'm doing it) and run It's collector output right back to the base of the front end amp. Now you got aiding feedback minus the shift from the RC network but you can adjust it with the variable pot. Then run the output of it all through a diode, maybe a nice low voltage germanium diode. Then make some sort of audio amp config. Right now I got a 3904 and an LM386 to head phones. It will drive a speaker but not enough. I might throw another stage in it. I was just listening to Pastor Pete Peters on short-wave! There's a bunch of stuff on there and it is so simple compared to a superhet. It's just a fun toy but they work!

 

[Dragon Tamer]

You know, I thought you had said superhet at first. So if you know something....spill it!

...I didn't do it! I never touched the resistors! (I had a discussion about this with my friends, we found out that I'm the only person that's a big enough geek to steal from radio shack)

OK, now you guys got me all excited! Did somebody say radio? Hell, I'll take a radio over a girl any day. Guess I finally reached that age ....Oh well.

Don't feel bad, sad thing is sometimes I'm that way to.

Thanks for offering to help with the clock that you posted, the problem is like I said; this isn't always going to be plunged in. It may go for months without power, so an old alarm clock with battery backup built in would be perfect for me. I saw an old radio in the electronics shop where I get so smarts,s... [looks around nervously] I was going to see if they would be willing to sacrifice the IC that was used for the display. I think that they already took everything that they wanted from it (IE: speaker, display, transformer, you know big stuff) I'm hoping that they would be willing to give up just the timer IC and I will rebuild the circuit. It's a start towards what I want to do.

The other thing is, I could make the clock out of some counter IC's like the 4029 and 4511 and just have a precision 1 second clock pulse going into the clock pins. Do you know how to make a precision clock?

 

[Space Varmint]

...I didn't do it! I never touched the resistors! (I had a discussion about this with my friends, we found out that I'm the only person that's a big enough geek to steal from radio shack)



Don't feel bad, sad thing is sometimes I'm that way to.

Thanks for offering to help with the clock that you posted, the problem is like I said; this isn't always going to be plunged in. It may go for months without power, so an old alarm clock with battery backup built in would be perfect for me. I saw an old radio in the electronics shop where I get so smarts,s... [looks around nervously] I was going to see if they would be willing to sacrifice the IC that was used for the display. I think that they already took everything that they wanted from it (IE: speaker, display, transformer, you know big stuff) I'm hoping that they would be willing to give up just the timer IC and I will rebuild the circuit. It's a start towards what I want to do.

The other thing is, I could make the clock out of some counter IC's like the 4029 and 4511 and just have a precision 1 second clock pulse going into the clock pins. Do you know how to make a precision clock?

Well, remember what I said. I will help you with it if you like. There is another clock on here a guy did that was really nice. I cannot remember his name but he did an exceptional job. You should be able to go into the search box and type in "clock" and find it. But no need to sacrifice anything. The point is you need something that will produce seconds. If you go over to my "Frequency Counter: post, I have a 32KHz low power oscillator circuit you can snag right off the design. It will produce seconds. After that, how you want to display it is the last deal.

 

[Roff]

You know, I thought you had said superhet at first. So if you know something....spill it!

The differences between regen and superregen are described here. You can Google for more info.

 

[Dragon Tamer]

I was poking aroud google looking at the different schematics of digital clock circuits and a persitant problem continues to come up, none of them have battery backup to remember the time. So let me ask a question; can your clock circuit remember and keep track of the time once the main power is removed?

 

[Space Varmint]

I was poking aroud google looking at the different schematics of digital clock circuits and a persitant problem continues to come up, none of them have battery backup to remember the time. So let me ask a question; can your clock circuit remember and keep track of the time once the main power is removed?

Mine runs off battery. I tested it up to about two months without changing the batteries. It was actually part of something I was building for a customer that has a motion sensor and all. Naturally the motion sensor killed the battery performance. You have to amplify the piss out of those things.

 

[Space Varmint]

Hey Guru? I decided to put some AGC on it. Not done yet but seems to help out allot. I took it off the RF output back to the front end. Still working with it but appears to level off the carrier enough where I was able to observe that the higher the feedback the more selective they become. Down around 3.210 MHz there are two very strong stations only 15KHz apart. Very difficult to keep them from intermodulating with each other.

 

[Space Varmint]

Hey Guru? I decided to put some AGC on it. Not done yet but seems to help out allot. I took it off the RF output back to the front end. Still working with it but appears to level off the carrier enough where I was able to observe that the higher the feedback the more selective they become. Down around 3.210 MHz there are two very strong stations only 15KHz apart. Very difficult to keep them from intermodulating with each other.

edit*

I need some amplification. What do you think about an LM1458?

 

[audioguru]

An LM1458 is simply a dual lousy old 741 opamp that has a poor high frequency response, a poor common-mode input voltage range and is very noisy (hiss). A TL072 is a dual hi-fi opamp that is inexpensive because it is (was) used in many hi-fi systems.

 

[Space Varmint]

An LM1458 is simply a dual lousy old 741 opamp that has a poor high frequency response, a poor common-mode input voltage range and is very noisy (hiss). A TL072 is a dual hi-fi opamp that is inexpensive because it is (was) used in many hi-fi systems.

Ah crap! That's all I got in my junk box right now.

 

[Dragon Tamer]

Well, I've found an IC that can work off of the 60Hz AC signal, the LM8560. And the best part is one of the companies that make it is Sanyo! That means that it'll work perfectly with my crap Amplifier! I've been looking at the clock circuit that you've posted Space Varmint, I've downlaoded all of the files and I'll save it for a little later once I get a little bit of a better understanding of the programing world.

 

[audioguru]

Isn't your shoe-box radio a portable battery-powered one?
Then the clock with up to 30 LEDs lighted will eat the battery in 15 minutes.

 

[Space Varmint]

Isn't your shoe-box radio a portable battery-powered one?
Then the clock with up to 30 LEDs lighted will eat the battery in 15 minutes.

Yeah those LEDs pull some power over LCDs which pull none. Most use a back light scheme. The luminescent types are cool in that the back light is low power but you have to use a DC2DC converter. I think you need 200 volts. Not sure. Someone will know.

 

[Dragon Tamer]

during battery backup, the LM8560 stops displaying the time. Although, the data sheet seems incomplete, the schematic has traces that go no ware.

 

[audioguru]

The digital clock IC is made for a main-powered clock. The battery just keeps the clock "ticking" without the display that would kill the battery in a short time.

Many years ago I saw a watch with an LED display. It had its display turned off most of the time and you pressed a pushbutton to light it for a moment.

 

[Dragon Tamer]

This clock was dug out of the bottom of a pile of junk that had been sitting around for the past year and a half, I plugged it in and it immediately started displaying the correct time (give or take a few minutes) All it was working off of was a single 9V battery (it was almost dead when I found the clock, 7.3V) I'm fully confident in it's ability to operate off of the the battery pack that is going to be installed in the box. That battery pack is a 12V battery and I could just tap the battery for power at about 9V. Although I do have a question about the circuit in the data sheet. For the circuit for the positive power supply, if I use a Bridge rectifier instead of a full wave, could I still use the center tap as the signal for the clock?

 

[Dragon Tamer]

Space Varmint, I took another look at your clock circuit that you showed me (PS: don't include your name in your schematic, at least not your real name) and I have concluded that you can use the MAX7219 to drive an LED display instead of an LCD display. The MAX7219 has a similar pin configuration as your AY0438. (you may want to double check though)

Here is the data sheet.