pre-"real-time" VCR counters

[AidanLunn]

I was wondering if anyone could explain these puzzling anomalies for me?

In this thread I'm referring to the older VCRs, the counters for which would count from "0000" to "9999", without giving an indicator of the units of measurement.

Firstly, what is the unit of measurement? Is it a physical length of tape rather than a measurement of time?

Secondly, is there a way of converting this counter into hours, minutes and seconds?

I originally worked it out that every "900" would be roughly 25 minutes worth of tape, but it seems that there are wide variations in the speed that these counters work at, depending on the model of VCR (incidentally, I worked this out on a Sanyo VTC5150).

Many thanks.

[Michael Maurice]

The way these counters worked either the early mechanical counters or the later electronic ones was that the counter was based on revolutions of either the take up or supply spool.

There was no standard and a count from the beginning of the tape on one machine was completely different from the count on another machine.

Later, the designers decided to use a counter based on the control track which is a proper real time counter.

[paulsherwin]

As Michael says, the counter value is an arbitrary number and doesn't indicate a specific length of tape. The counter will turn more quickly at either the start or the end of the tape. The behaviour is identical to the tape counters used on most domestic R2R and cassette decks. (Professional R2R decks do often have true real time counters.)

[Sideband]

The mechanical one's obviously just turned a mechanical counter. The digital ones operated from either an LED sensor or a hall sensor usually on the take-up reel. The speed of this varied according to the amount of tape on the spool so there was no proper relation between the number to the amount of time used. It would also depend on whether you used E180 or E240. The idea was to give you a rough indication or where recordings started and ended assuming you zero'd the counter each time you started a new recording. Most of them had a 'zero stop' button so when you start a new recording, zero the counter then when the recording is finished you press the 'zero stop' button, rewind the tape and it stops at counter zero. With luck, you will be at the start of your recording.


SB

[AidanLunn]

So presumably the switch to real-time counters was one of the reasons to change VCR operation to constantly threaded tape when a cassette is inside the machine?

[Sideband]

Yes that would be one of the reasons because the tape has to be in contact with the A/C head.



SB

[paulsherwin]

Also, the progressive shift from mechanical to electrical/electronic operation explains a lot. You don't need to have the tape permanently laced around the head to provide a real time counter, but you do need to have it laced around some sort of external wheel to measure how much tape is being wound.

[John123]

I remember the Ferguson 3V23 had 12 used time/ time remaining dots to compliment the standard tape counter.
So for example, with an E120 one dot represents 10 minutes - that's actually if there was 12 dots in total, I can't remember! And our machine was faulty, so the dots would do a merry dance

[Welsh Anorak]

Hi
Some early high-end machines featured real time counters but (understandably) the manufacturers were reluctant to have the tape constantly round the video heads and so had a dog-leg lever that kicked the tape round the audio-control head.
One drawback of real-time counters is that the tape needs to be recorded - i.e. have a control track. If, say, a half-hour programme was recorded on a three-hour tape and it was fast forwarded to the end the counter would stop at 30 minutes despite the tape still being wound! This caused some confusion...
Philips used a different system (what a surprise!). This counted the revolutions of the supply AND take-up spools and calculated the point at which the tape was, hence the prolonged shuffle of a tape on insertion. This got round the presence (or absence) of control track pulses, but of course there was a drawback in that you needed to tell the machine what length tape was there (E-180, E-240 and so on). Usually not a problem, but pre-recorded tapes fooled the machine completely!
Glyn

[8 Tracker]

Didn't the Philips V2000 cassettes have holes and blanks in the cassette shell which pressed different switches on the deck to tell the machine what length of tape had been inserted (amongst other things)?

Mark.

[Welsh Anorak]

Hi Mark
You're right, and the V2000 system featured a really handy 'goto' feature. Not sure if any late 2000 series featured real-time counters, though - the 2020's counter was arbitrary.
The Philips system I was referring to was their later VHS one in the high-end Turbo decks which worked very well.
Glyn

[murphyv310]

Later VHS machines on FF & RW would have the tape in contact with the CTL head, this was done using a "half loading arm" so the control track could always be seen.
It still wasn't accurate. Later still the speed of both the take up and supply reels along with the CTL pulses were compared to give a reasonably accurate time display.

[8 Tracker]

Hi Glyn,
I remember the "go to" function on the V2000 machines well. They had a direct entry keypad and you could type in the required time and just press the button - a great system. Was this present on later machines? I have a VR2220, the portable one, which doesn't have a numeric keypad. I always thought this was the reason it had no go to function. It doesn't have a real time counter. Was there any other reason for the machine to know what length of tape it had in it?

Trevor, my Hitachi VT520 has the half loading arm and calculates time remaining on the tape after it has been playing for about 30 seconds. You have to tell it if you are using a 180 or 240 minute cassette though. It is quite reliable, though always underestimates by about five minutes. Better than missing the end of that film when the machine says you have ten minutes of tape left. It keeps time well during search or wind operations. I have four of these, they are all the same, about five minutes out.

My Sanyo VTC6500 has five lights to indicate length of tape remaining. They all flash in a pretty pattern until the machine has worked out how much time is left. The display uses pulses from the take up reel. The only problem is that any use of picture search or FF and REW resets the display and it has to start again when play is pressed.

Mark.

[toshiba tony]

with reference to lacing up and tape counting many machines partialy laced, ie, round the ac head only, this also took advantage of the next and previous recordings on the tape

[Studio263]

The Sony open reel VTRs had a real time counter and it was really simple, the counter itself was the usual mechanical type but instead of being driven from one of the hubs it was driven from one of the rollers that the tape went around, how easy is that?

The B&O VX5000 / 5500 have a real time "tape remaining" function that works by measuring the rotation of both reels, you only have to tell the machine if an E240 tape is loaded, it seems to be able to work out the others for itself. There is no shuffling about but it does take a few seconds in play / record to get an initial reading.

[Michael Maurice]

Originally Posted by Studio263

The Sony open reel VTRs had a real time counter and it was really simple, the counter itself was the usual mechanical type but instead of being driven from one of the hubs it was driven from one of the rollers that the tape went around, how easy is that?

The problem though in a VHS deck is space to put another roller that is tightly in contact with the tape.

It wasn't until 1989/90 that half laced machines became available.