Cheap´n small 2 kHz tone generator for sync pulse recording

[mattias]

the mic plug, that every MD should have. Line would be too good, but I saw devices in the stores, which havn´t any.

it's actually the other way around. virtually all md players (i.e. sony et al) have line in, but only a select few (i.e. sharp) have a mic jack as well.

/matt

[mattias]

With all respect, complicated? - no.

you need to look up complicated in your dictionary. i never said it was too complicated for you to understand or anything. it *is* rather complicated to build though, even for a skilled engineer, in that it requires quite a few different components and takes a while to put together. this is why i suggested isolating the signal generator part and builing only that, which is trivial. especially for a guy like you i'd assume.

S8 filmmaking does. I just buy off the shelf what there is available and now this is the thing I want and need - not Pedro´s.

look, i'm not saying you're wrong or anything, i'm just saying that if you just need the tone generator and not pedros complete design, you can easily build one from a 555. you still have to attach resistors, potentiometers, a battery, cabling and so on to your device, so you can't escape your profession anyway. ;-) the reason i'm keeping this somewhat empty debate running is that i'm curious, and that i'm always trying to keep the information accurate, which your claims about your device being a more convenient solution really isn't as far as i can tell...

/matt

[S8 Booster]

Well, OK Mattias.

The case is, I think that my approach to this is different from that of Pedro´s as the pure tone generator only will be a out of the box tool for:

- those who basically only need a simple an one piece/block tonegenerator for sync pulse/NLE edit.
- my portable on-board camera MD recording system which is, as I see it, very different from what the utilisation of Pedros system is intended for.

I will not use this pulse sync system to implement to anything else than the on board camera/MD unit and NLE sound edit.

The tone gen unit I use will get physically added on it:

2 x 2.5mm Mini jack printboard type sockets: 1 for power (battery) input + one for flash sync line input.
1 x 3.5 mm mini jack for pulse signal output to MD line input.

In addition the 6.2v Photo Lithium one cell battery (very small) and worst case, 2 resistors for balancing the output signal to the MD.

I am actually considrering to use the cams 9v built in battery as a power source by a small 2.5mm mini jack output from the battery compartment thus eliminating the on unit battery power. Will be deicded later.

There will hardly be be any superflous wiring at all: distance from Flash contact to Tone gen: less than 5 cm, 1 plug in wire. Distance from tone gen to MD T jount input: less than 5 cm, 1 wire. Connection between mike and MD is by the original mike wire via a T joint that collects the sunc pulse wire also.

The tonegen + acessories will be 1 unit only. The tonegen and the MD will be detachable from the cam by "american zippers" (never remember the proper name).

it is actually the physical shape and size that makes it fit like a glove to my system, nothing electronic/electrical or the signal itself.

I will get a compact and rugged basicaly of shelf one package unit with a minimum of wiring and complexity. The tonegen will be mounted underneath the rear of the cam, just like eh.. the battery on a digibeta! ?

It can also be mounted on the on board mike. Very good space for it there and it is more out of the wayfrom everything but there will be somewhat longer wires. No big deal though.

Not "selling" a "superior" solution, it isn´t except for me and or maybee those who only need a compact and easy to connect 1 piece tonegen for a pulsetrain.

Just trying to straighten out the possibly different angles of approach?

OK?



Might add that it is possible to use an additional mike preamp with extreme channel separation and S/N ratio that connects to the MD via the optical MD input so pulse noise can be elimited 100% worst case if nothing else works.

R

[mattias]

thanks a lot. that's what i wanted to hear. ;-)

(i still don't understand why you think i'm suggesting you should use pedro's circuit though. i've never said that, but rather quite the opposite)

good luck, and let us know how it works out...

/matt

[S8 Booster]

thanks a lot. that's what i wanted to hear. ;-)

(i still don't understand why you think i'm suggesting you should use pedro's circuit though. i've never said that, but rather quite the opposite)

good luck, and let us know how it works out...

/matt

Sorry, my mistake, the scanner "overheated". (Just did not read your post carefully enough)

I agree on your tonegen design. It will work very well and you are right about the wiring extras too. It is not any problem with that. I picked mine also because it is packed in an one compact molded "all weather" design unit although my cam and MD are not!

I will post samples when I get there. TNX.



R

[Guest]

S8-Booster,
only some remarks to avoid misunderstanding:

1. I did not to make any competition with your solution. Your solution may work very well with your particular system be perfect for you.
I only nearly colapsed when I read what you payed for a "primitive" tone generator circuit - that maybe beyond of my horizont.
And I tryed to transmit, that the pure electronic device is never enough when it comes to use it in real life, away from the lab. 50% of the work of any electronic device are that "trivial" things like box, fixing, plugs, ergonomy etc. That´s what partly makes prof eqipment more expensive.
So, only a "ready to use" and "out of the box" tone generator is only the half of the way, but you will see.

2. I am not really selling nothing comercially. I started answering to questions about double system sound and tryed to show interested people do it yourself solutions. Many asked me to build the stuff because they did not want to bother with electronics. Specially the MD interface I built so many times for guys all over the world, and I only got positive feedback. But it´s taking to much of my time and I am really prefering to pass foreward only the diagrams.

3. I looked in electronic stores about low cost MD recorders, and I found out, that they have mic inputs but no more analog line inputs, only optical. Therefore I decided for a more or less universal solution to design the sync output for mic inputs (about 2 mV at 1kOhm). But no problem to realize a different level and impendance if there were changes in the market.

Your mike with in-built amp (line-level?) for shure is very special (I did not know that), as well as the control out socket of the Canon (I know this socket) with remote pins and power supply. So you don´t need any battery, only to find the male part for that socket and mount everything into that plug. Standard for any camera would be a flash socket only.

4. remote control of pause etc. is not possible by flash pulses only. The minimum is a monoflop to produce a constant, not alternating signal, that becomes "high" with the first flash and keeps "high" as long as other flashes are following within the determined monoflop time. To control pause and play, it might also be neccessary, to create two differnet signals, one at the rising edge for the play button, another at the falling edge for the pause button.
But again, not neccessary with your canon, but for an universal design yes. What you might need for remote control is an opto coupler to isolate the camera potential from the recorder potential.

5. concernig the operation ergonomy of modern miniature consumer electronic, I personally have no problems with tiny displays and complicated menues. But without any doubt, this is slower and less direct accessable than a dedicated simple button or knob. When it comes to hectic shootings, f.e. for reporters etc, this may be quite disturbing.
I personally know a reporter, who told me that in the radio station they made a kind of "revolution" when the station had been trying to exchange the Sony WM-D6C and TC-5 recorders to MD. Now they are with their tape recorders again. It´s all a question of quick and easy access to the needed funcions, even in dimm light or under stress. Again, here prof. design differs from consumer electronics. Perhaps your Sony MD is one of those rare highlights, I don´t know. The cheap Aiwas are not.

6. the further use of the sync signal made of tone pulses is not limited to nle. If recorded properly, they are good for any double system sound. So the application is the same, no need to differenciate.

7. for quality recordings it may be better to bring the mic close to the sound source instead of keeping it close to the cam. A practical solution is to put the complete audio equipment into a small bag and connect it to the camera by radio remote (f.e. 433 MHz).

One advise you may accept:
avoid any 2,5 mm jacks! They only cause troubles (contact problems)! Much better are DC-jacks. Even the 3,5 mm jacks are not a very good solution, but unavoidable. Profs only use lockable DIN plugs, BNC plugs etc.

Pedro

[mattias]

I looked in electronic stores about low cost MD recorders, and I found out, that they have mic inputs but no more analog line inputs, only optical.

wrong, they just use the same input for both. i recently tried out several models and finally bought one, so i know what i'm talking about. i have never ever seen a md recorder that didn't have line in, although i've seen several without mic in. however, if you're sure about what you've seen i'd love to be proven wrong with some hard facts. which models did you research?

/matt

[S8 Booster]

I looked in electronic stores about low cost MD recorders, and I found out, that they have mic inputs but no more analog line inputs, only optical.

wrong, they just use the same input for both. i recently tried out several models and finally bought one, so i know what i'm talking about. i have never ever seen a md recorder that didn't have line in, although i've seen several without mic in. however, if you're sure about what you've seen i'd love to be proven wrong with some hard facts. which models did you research?

/matt

Mattias is absolutely right.

I only know the Sony 700 and 900 MDs but they switch automatically using the same input socket. It you plug in a mike the "mike" indicator comes up in the display and if you plug in a line-in device the "line" symbol comes up. There is a detecting curcuit on the MD input that switches automatically between line and mike settings.
It can be seen on the Sony documentation.

The manual gain control is available for both settings on the 700.

The Sony booklets and info are not complete on this. I believe it says that the 900 has but the 700 has not a switching device. However, I asked the support people at sony.no and they told me that 700 use the same system which I can confirm it does.

R

[S8 Booster]

The sample below was recorded with exactly the same setup as shown above ex the tone generator device.

Recorded via the original on-board mike directly to the MD mike input. Gain was set a little to low. Test only. Camera running (filming in sections of the recording) Not really audible cam noise. Possibly audible using a head set. Plenty good for any homemovie.

MD sound sample:
ftp://ftp.filmshooting.com/upload/audio/MD%20TEST.aif

Additionally:
It is possible to reroute the mike via the camera´s preamp and plug the Cam monitor output into the MDline input. This will allow use all of the cams sound control systems like Auto Level Control, Manual LC with limiter, manual without limiter, -20dB, and bass cut filter.

Unfortunately the monitor output seem to produce some transistor hiss noise which is absent on the film stripe recording (when they were available) but even with some hiss it is plenty good for home movies.

Another great feature with some MDs is that they can store the recordings by filename+date and step from track to track very quickly. Using a MDH-10 with SCSI interface for playback will allow digital transfer (fast transfer rate) to the computer for sound edits too.

R

[Pedro]

About 3 or 4 years ago, when I had been looking for a solution for really synced sound instead of wild sync, I held some Sharp models in hands, the only ones, I could achieve. At the ceapest model for recording, I only noted a mic and an optical input. But I did not like at all the design of control elements and general use. Furthermore, I thought that stereo sound gives a lot of more deepness to the sound tracks, and last but not least, I wanted a device with the possibility to speed regulation. So I abandoned the MD idea totally and did not follow this way anymore. Instead of that, I started searching for a Sony WM-D6C recorder, got one and let it convert to AV. I am still very happy with this solution, I can operate this device "blindly", only putting my hand into the camera bag where it is. I can record stereo sound with separate sync track in best Dolby C quality, I have manual gain that I can control without looking at any control instrument. Only setting the headphones to level "4" and hearing is enough. The same way you hear it in the phones, it is on the tape. The device is coupled wireless with my cam and switches on automatically when I trigger my cam. After releasing the trigger, it continues recording for more 20 seconds, to have more audio for later editing. Normally, with Dolby C, I always can leave the gain in 5..7. For very best dynamic, I use the headphones and set the gain short before distortion starts, turning the easy to find knob.
I really love this very practical solution, for me there is no need for expensive K40S stock and no need for MD.

Btw,
hiss and distortion out of the cam´s monitor output maybe because the impendances are not combining with the MD-input. A look to the cam spec may help here, and then adapting the impendances, using a small audio transformer or give it a try with resistors.

Pedro

[S8 Booster]

Btw,
hiss and distortion out of the cam´s monitor output maybe because the impendances are not combining with the MD-input. A look to the cam spec may help here, and then adapting the impendances, using a small audio transformer or give it a try with resistors.

Pedro

No doubt that your setup works excellent. Some of the rasons for choosing the MD is the possibilty of using the elegant on-board MD recorder. The unit is a one-touch protruding single button record function. The Pause button is too blindly acceessible as well so this is no problem with this MD. It will also add a new track for each recording which makes it easy to search and name the tracks later.

Since I want primarily to use the cams very good pre-amp and control systems and original "boom mike" I have no problem to give away the stereo for that and besides using a NLE edit/sound edit allows to create extremely good (better) stereo from mono recordings. Piece of cake.

The hiss is really a monitoring curcuit problem, checked with headset and original earplug so it is there. See if I am going to improve it but it is not so evident that it is a problem for homemovies.

It is actually possible to set the sound manually to that the hiss goes almost no-noticeable anyway.

The setup is intended for "action shooting" and homemovies. For "serious" shooting I´d go for a HQ boom mike and possibly using a combined XLR A/D preamp with optical wiring to the MD.

I have no problem in accepting other "shooters" using A-tape or DAT or any other recording media. I went for the MD and both like it more and more and get even more impressed by it by the day.

R

[mattias]

About 3 or 4 years ago, when I had been looking for a solution for really synced sound instead of wild sync, I held some Sharp models in hands, the only ones, I could achieve. At the ceapest model for recording, I only noted a mic and an optical input.

i've used cheap sharp md recorders for about 4 years, and i can assure you that a mini line plug fits just fine in that optical jack.

there is of course a slight possibility that you've seen the very odd model that's actually the exception to the rule, and in that case i'd really like to know what it was called so that i don't make this mistake again... :-)

/matt

[S8 Booster]

never ending story?

OK here it is then besides the Mike-mike input with auto bias.

[Pepo]

Hi people.
I've been folowing this discussion.
Earlier I posted a message asking how to get a mono open reel recorder in sync with image.
I understood from your posts that you recorded a pulse together with the audio track (like Nagras do). However, I can't imagine how do you control the speed of the device for it to be exactly at the same speed when palyed back as when it was recorded, because that is what a pro-film sound recorder does.
My recorder is an Uher 4000. Could any of give me some info on this.
Thanks a lot
Pepo

[Pedro]

Hi Pepo!

Well, playback and editing with open reel machines and projectors is a very fascinating story and there are several
systems, aproved over many years.

To understand it, you best imagine a mechanical flat desk editing setup. This kind of setup has at least 2 film reels
and two tape reels. The tape is diferent to standard 1/4" audio tape, it looks like a film (16 mm, S8 or 17,5 mm large)
with perforation holes. Now there is a sync block, nothing else than a sprocket drive, which drives both tapes, film and
audio tape together. The sprocket holes of the tape and the common drive garantee perfect sync.
It´s obvious, that the live sound for that system must be recorded on such a perforated tape the tape must had been
coupeled electronically to the camera during shooting.

Modern digital editing tables work without mechanical sync drives, sync is achieved electronically. All of them have
the architecture of a master-slave-system. One of the partners, film or audio, must be the master who determines the
exact framerate. The slave has to follow up and sync to that given framerate.
When the audio is master and the film is regulated slave, the system is called "foreward regulation".
When the film is the master and the audio follows up as slave, it´s called "backward regualtion".

No matter what kind it is, the heart of the system is the so called synchronizer. This device contains an digital counter
with two inputs. One input increases the result of the counter which each impulse, the other input decreases the result
which each pulse. The ouput result is used for influencing the pitch adjustment of the slave.
To make it work, you must connect your master device, f.e. the sync pulse track of your audio, to the up-counting input,
and your slave device, f.e. your film projector´s single frame contact to the down-counting input.
When both devices are running in sync, the master input increases the counter with each pulse and the slave input
decreases it again with each frame projected. So the counter result keeps unchanged, and the pitch signal for the projector, too.

You see, there is no need to make any regualtion during shooting! The tape only registers the way camera had been running.

If the projector should be too slow and would loose sync within a few frames, it will not be able to decrease the counter
by the same number of frames the sync track had increased it. The counter will show a diferent result, causing a
pitch regulation of the projector. The projector will speed up to neutralize the counter result again.

This is the way, foreward regulation works. You see, you need your tape recorder, a synchronizer and a projector that
has a flash contact like a camera and an compatible interface for pitch regulation. The Elmo GS1200MO has it all, it
even has an inbuilt synchronizer. You only connect your sync track, using a small converter, to the ESS input of the Elmo
and are set up.
Bauer T610,T502 and T525 can easyly be modifyed to interface to a synchronizer. Braun Visacustic projectors just interface
to a synchronizer from factory. Other projectors, as long they have a regulated DC motor, can be interfaced individually,
but the effort is significant.

For backward regulation, any projector, even hand cranced, can be used. The only condition is, that it must have a flash
contact (reed contact or opto coupler). Now the projector is master and the tape will have to follow. For this reason, the
tape recorder must be adapted for external pitch regulation. This can be done for Uher, Teac, Tascam, Sony WM-D6C and TC-5
and others by Gebuhr in Nürnberg/Germany.


For editing, the projector is going to be substituted with a multiple track tape machine (f.e. Teac A-3440), loaded
with 1/4" perforated tape. When running such a tape f.e. at 19 cm/s, the perfo holes will pass by exactly at 24 holes/sec.
Now you only scan the perfo holes with an open beam opto-coupler and use them to report the actual framerate, or to identify
a certain frame number of your film. You now can transfer your live sound in sync to that perforated tape, add more sound
the the 3 other tracks. When transfering back to the film, the synchronizer matches again the speed of projector and tape deck
and mix the sound to the sound stripe.

Pedro