LM567 circuit

[wleggett]

I am trying to design an audio detection circuit that uses an mp3 player to control multiple devices using audio tones on the left channel and pre recorded audio on the right. Like a halloween animation with music playing. The tones to detect are generated using a program on a laptop ranging from 1000Hz to 20,000 Hz. Separation would be 5000 Hz. So, 1000, 5000, 10,000, 15,000, 20,000Hz for the tones. I am hoping the 567 will have a tight enough bandpass to separate the individual tones. I want to control 4 separate servos. I have the 555 timer circuit for controlling the servos, similar to the 'scary terry' circuit. I need detection of each tone to trigger the servos to move. R-C bandpass circuits are not tight enough for the frequency range of the software.

 

[ronv]

Seems like the 567 should work. What's the problem?

 

[MikeMl]

I would use frequencies that are not harmonically related, kinda like touch-tones.

 

[dr pepper]

The '567 is a good little circuit, but reasonable complicated to design a circuit for.
Your idea ought to work, just as mike says avoid 5kc and 15kc the 15kc might see a 5kc signal as valid, go for freq's that are not multiples of each other.

Speaking of touchtones I think this might be a better way to go for your system, the 8870 is a nifty little chip I've used them before, with just a couple of comps you can get them to work, the chip will give a binary o/p when it 'hears' a 'phone keypress, if you use 2,4,6, and 8 then you wouldnt need any other decoding, just the chip and a few comps, you could use the speakerphone on your mobile to produce the tones, I did this for a door lock system and it works well.

 

[Roff]

Holtek HT9170 is a DTMF (touch tone) decoder. I haven't used it, but I believe it would be a better solution than an LM567.

 

[dougy83]

Speaking of touchtones I think this might be a better way to go for your system, the 8870 is a nifty little chip I've used them before, with just a couple of comps you can get them to work, the chip will give a binary o/p when it 'hears' a 'phone keypress, if you use 2,4,6, and 8 then you wouldnt need any other decoding, just the chip and a few comps

Using a DTMF decoder does seem like a very good idea. No other decoding is required ever; 1, 2, 4 and 8 keys would switch each output on individually, while the D key would clear all outputs. Every other key can be used to provide multiple output activated at the same time (e.g. the 3 key will activate the first and second outputs).

 

[wleggett]

Thanks Roff! I looked at the data sheet and it seems the output will latch until the next tone is heard. This is not good for controlling a servo. To get the jaw moving action in sync with the audio, I need the output to go low when the tone is lost.

Dr. Pepper, Do you have a schematic in mind? Thanks for any help!

MikeML, A great thought. I have not used the '567 yet, but just received them in the mail and will start building tomorrow.

ronv, my problem was in not knowing the tightness of the bandpass filtering that I can get from the 567 IC. I will start playing around with it tomorrow.
Do you have the formula for calculating the components for each frequency range? 1700Hz, 6500HZ, 11000Hz and 18000Hz??
Schematic example maybe?? THANK You in advance!

Thank you for all the info!

 

[MikeMl]

The applications section of this data sheet has some relevant circuits. I might go with touch tones just because you can use an old Bell phone (or other touch tone encoder) to generate your tones... You can obviously just use the a single tone (not two simultaneously) to control your various outputs...

 

[jpanhalt]

I appears that you are choosing the frequencies you want to discriminate between based on what a human can presumably hear. The scale is not linear as to perceived note. Moreover, since you want to sync to music and other commonly audible sounds, you might want to consider a somewhat lower scale.

Check here: https://www.phy.mtu.edu/~suits/notefreqs.html

In other words, if your puppets had different actions for 11,000 and 18,000 Hz, most of your viewers wouldn't get the point, and a very high percentage of them would hear nothing.

John

 

[Roff]

Thanks Roff! I looked at the data sheet and it seems the output will latch until the next tone is heard. This is not good for controlling a servo. To get the jaw moving action in sync with the audio, I need the output to go low when the tone is lost.

The outputs are latched, but DV (data valid) is only high when a valid DTMF signal is present. This can be used to reset the output.

 

[Roff]

I appears that you are choosing the frequencies you want to discriminate between based on what a human can presumably hear. The scale is not linear as to perceived note. Moreover, since you want to sync to music and other commonly audible sounds, you might want to consider a somewhat lower scale.

Check here: https://www.phy.mtu.edu/~suits/notefreqs.html

In other words, if your puppets had different actions for 11,000 and 18,000 Hz, most of your viewers wouldn't get the point, and a very high percentage of them would hear nothing.

John

The way I read the original post, the control tones would be on one track of a stereo recording. That track would not be sent to a speaker. The other track would have the audible audio.

 

[jpanhalt]

Got you. I missed that point. Why not just pre-record the sync'd movements using something like shown in post #3 here: https://www.edaboard.com/thread215058.html

There are some other threads and links to similar things in my files. Let's see what the OP thinks of that approach. I think it would allow much finer and more complex control of movements than a simple, 4-position model based the 4 programmed frequencies.

John

Edit: Even easier, you could probably pull the pre-RF signal from a typical RC transmitter (e.g., trainer cord) and put those on the left channel as data. Then reverse the process at the output with a receiver.

Added 01.3.13: Here is one preliminary report on adapting a commercial MP3 player to data logging, That might be of interest if the OP takes the approach of recording a choreographed sequence of servo movements. https://www.electro-tech-online.com/custompdfs/2013/01/FP_532.pdf

 

[dr pepper]

As an industrial electrician I've worked on various gear, some older paint spray booths have recordable robots, someone sprays whatever needs painting with a spray gun attached to an arm, their movements are recorded on tape and 'played back' by a robot every time a new item needs painting.
Similar methos to what you mentioned.
Of course this stuff is 25 years out of date now.

 

[wleggett]

I used to work at MOOG Aerospace and Hydro-point in CNC milling machines and alot of the control stuff from back then can be updated and used for DIY animation for halloween. I teach electronics in Western New York at a vocational school for 11th and 12th graders. It's VERY obvious that electronics at this level is going away and any of the younger generation that wants to enter the field will have to go to post secondary school to start learning electronics. My student won 1st place at the SKILLS-USA electronics National competition in Kansas City last year and he had 35 other states sending competitors. It used to be almost 50 states would send. Some still have strong programs, but repairing electronics is a lost art left only to very high priced industrial units that are supported by their manufacturers. I'm still trying!!!
Thanks for your help!!!

 

[wleggett]

I have the ability in my classroom to etch circuit boards and want a circuit for each student(15 usually). They can get the skulls for $2.00 and Dollar General stores and the IC's can come from my budget. The servos are the expensive parts and I am looking for an implementation that stays away from micro controllers and programming. I use Automation Direct PLC's in class and teach Motor control and LOADS of residential wiring. I cannot fit time in to get into PIC's or anything much more complex. Teaching Ladder logic and programming for the PLC's takes three months. I have been told to add Solar and Wind Generation to my class and have to cut back in the electronics section to fit it in.

 

[jpanhalt]

First off, thank you for the additional information about what this project is being used for and your location. With that background, I think the analog solution using LM567's and fixed rotations will work fine. It sounds like a really fun project.

I do have some reservations, mostly from ignorance, about how MP3 will work at 20KHz. But that is a small point. You can surely find 4 frequencies that the 567 can readily separate.

Now as for servos, what do you consider expensive? Do you need new or can you use used? Used servos can probably be had from a local modeler's club for free or very nominal cost. Most clubs during the Winter have trade fairs and yard sales. Knowing it is for a school project, many members will probably just donate them. Otherwise, functional used analog servos can probably be had for less than $2 each. For most of us, used servos have very little value, and one that has been in a crash may be deemed worthless for anything of value that relies on it. The main problem with used servos is the supply may not be consistent from year to year. You may find that the servo electrical connectors and pins end up costing more than the servos.

So, what price do you need to meet for new servos? Is there a chance you could provide the servos for the class project, but require the students to return or buy them after the project is over?

John

 

[wleggett]

Thanks for the response jpanhalt. Actually, there is a local airplane club in Lockport , New York and I know someone in it. I will ask about the used ones.
Great Idea! The sinewaves at 20KHz get squared off a bit, so I stay below.
I will post to Youtube when we have '567 style working models. I have three units now, but the frequency bandwidth only allows two to operate at a time. We want to do the Abbot and Costello "Who's on First" routine with the skulls to start.
Bill

 

[wleggett]

Here is a test run using two skulls and 800Hz and 12000Hz to separate them on the Left channel. Works very well, but we want to add two more.
If successful, The next step is to combine frequencies at the same time (overlap) and have the individual skulls respond. As it is now, we do a strict back-and-forth for the audio. Like using walkie-talkies, can't both talk at the same time.

https://www.youtube.com/watch?v=GMiertieVQM

 

[dr pepper]

Excellent.

I wish we had such things at the school I went to.

 

[wleggett]

Been playing with 567 IC and it has a Very narrow bandwidth around 6400Hz of +/- 400Hz. Do you know if the bandwidth can be opened a little? The 1st Harmonic is there at 12800Hz , but not going to be a problem. I should be able to have Many different Skulls operating at a time! Thanks for all the info.
Bill