IDX-PRO+VDI

[paku]

New version of VDI.
Added input overflow control.
Added LCD backlight & contrast control using menu.

Thanks, HOLYUSER

[holyuser]

New version of VDI.
Added input overflow control.
Added LCD backlight & contrast control using menu.

[gtdavid]

Hello
I have finally got hold of an oscilloscope to tune my quicksilver cz coil can someone tell me what freq's I should shoit for and also is there a "how to" around for tuning a coil with a scope.
Thanks

[Gwil]

It is possible to remove the capacitor connected across the coil, and then drive it with a 555 set to oscillate at whatever frequency you like. The penalty is increased battery consumption, because now all the coil current comes from the power supply. With a parallel resonant coil/capacitor, most of the coil current circulates to and fro round the circuit, kept going by a comparatively small input from the transistor (as golfnut said, like pushing a kid on a swing).

[jlsilicon]

ok,
Thanks for the help Golfnut !

[golfnut]

its the same as pushing a kid on a swing

push a little or a lot - it takes the same time to do each swing


The R just sets how high the swing go's it cant alter the rate. (you need longer chain ,,,, or bigger L (or C) )



Im not sure I can help you further, Ive ran out of skill!

[jlsilicon]

Generally you need to switch caps to change the freq as it is a LC oscillator.
Look at some of the Tesoro designs for a 555 based oscillator. Here's a Lobo
schematic;
[ATTACH]32205[/ATTACH]

Yeah,
The lobo's later ID half looks a lot like the IDX.
And, I like the TX Osc.

Ok, 2 questions then,

One, the Lobo uses a series of triple 5532 preamp OpAmps, while the IDX uses only one 5534 as preamp OpAmp - Why ?
(Does the 5534 amplify more than 5532, or ... ?)

Second, how does the Lobo compare to the IDX in Depth ?

[Silver Dollar]

Generally you need to switch caps to change the freq as it is a LC oscillator.
Look at some of the Tesoro designs for a 555 based oscillator. Here's a Lobo
schematic;

[jlsilicon]

ok.

I just thought maybe that a resistor in series could Slow the Charging Time.
Is there no way to adjust the Freq with a Resistor, say 6KHz - 20KHz ?

Maybe a 555 Timer instead to Drive the Transistor/Base and so the Coil ?
- Do I need to remove the Cap then - and what do I lose in so doing ... voltage for example ?

Thanks for humoring my alternate ideas ...

[golfnut]

Golfnut,

Supposing, instead of changing the Coil and its Capacitor,

Could R7 of 100R be changed to a Pot of like 1K (instead of the 100R) to give an Adjustable Frequency,
- like P4 of 1K is trying to adjust the Freq ?
(Considering: R7 adjusts Charge Rate , while P4 adjusts Discharge Rate)

Calculations:
Pot set at 200R => 3.3KHz
Pot set at 100R => 6.6KHz
Pot set at 50R => 13KHz

Shouldn't this work ?

sorry boss Im a bit lost here..

post the schematic you use?


The main freq control is the coil L value and its resonating capacitor. R7 sets the current flow. this current, is pushed into the cap coil combo to keep it resonating, the resultant volts on th coil is about 15v peak to peak.

The oscillator is not RC tuned, rather it is LC tuned

[jlsilicon]

Golfnut,

Supposing, instead of changing the Coil and its Capacitor,

Could R7 of 100R be changed to a Pot of like 1K (instead of the 100R) to give an Adjustable Frequency,
- like P4 of 1K is trying to adjust the Freq ?
(Considering: R7 adjusts Charge Rate , while P4 adjusts Discharge Rate)

Calculations:
Pot set at 200R => 3.3KHz
Pot set at 100R => 6.6KHz
Pot set at 50R => 13KHz

Shouldn't this work ?

[jlsilicon]

With the IB VLF if the Rx is tuned to the Tx weird things abound. To make these usable the Rx coil must resonate a little away from the Tx..

often the Rx coil and cap is chosen to resonate at about ~66% of the Tx freq

Understand - thanks again !

[golfnut]

With the IB VLF if the Rx is tuned to the Tx weird things abound. To make these usable the Rx coil must resonate a little away from the Tx..

often the Rx coil and cap is chosen to resonate at about ~66% of the Tx freq

[jlsilicon]

perfect if you were doing about 8k Rx sounds good.

Sorry I am lost,
I am following your 12khz TX - so I assume same 12khz for RX ?

[golfnut]

perfect if you were doing about 8k Rx sounds good.