Barracuda Legend Kit Problems

[Old cart]

Hey guys i have my pc back to full health yay! so i can continue with the barracuda build, in the mean time i have made a coil with 0.5mm enamelled wire 14 turns wrapped with 1mm plastic spiral wrap and a mesh sheild taped on with paper tape, OK! so i have tried the coil and the movement issue is 90% gone but the coil is so slow i may as well just dig random holes at the beach with my son i will have better luck! but it is a step in the rite direction .

what wire would you sugest i buy? i have found this?

http://www.ebay.co.uk/itm/400814050318?_trksid=p2060353.m1438.l2649&var=670366097424&ssPageName=STRK%3AMEBIDX%3AIT

any good? or junk?

Does your shield have a gap in it so there is not a complete ring or closed loop around the coil? What kind of shielding are you using? As for wire that should be fine. It may not be as fast as more exotic solutions but it should be fast enough since coil speed is primarily driven by interwinding capacitance which is primarily determined by the spacing between each turn of the winding and also by the spacing between each turn and the shield. In your case you might try to layer two layers of the spiral wrap around the coil and apply the shield on the a outside of that being very careful to leave a gap of maybe 8mm between the ends of the shield.
Did you ever try the single shorted loop of wire experiment I described earlier?

[Old cart]

Well I do not wish to argue here. I just want to say if you put a resistor to 10V between 2 caps the voltage (between the caps) will rise to 10v.

[ATTACH]35544[/ATTACH]

The power pin of the 40106 must be at the highest potential of the circuit (IE 20v , +5V).

I believe this is the way it should have been done;

[ATTACH]35545[/ATTACH]

I see what you are saying. The spec sheet says the inputs should never be higher than the highest supply pin plus .5 volt. In this case that is ground so in your fixed schematic your connection to plus 5 IS ground and it should work fine and not violate ratings. Clearly the way this is designed violates that. You solution should fix that problem. The fact that the design works is merely a testimony to the fact that some brands or indivual chips can survive this abuse. I do not believe violating absolute max ratings is ever a good idea though.

[Impulse]

Hey guys i have my pc back to full health yay! so i can continue with the barracuda build, in the mean time i have made a coil with 0.5mm enamelled wire 14 turns wrapped with 1mm plastic spiral wrap and a mesh sheild taped on with paper tape, OK! so i have tried the coil and the movement issue is 90% gone but the coil is so slow i may as well just dig random holes at the beach with my son i will have better luck! but it is a step in the rite direction .

what wire would you sugest i buy? i have found this?

http://www.ebay.co.uk/itm/400814050318?_trksid=p2060353.m1438.l2649&var=670366097424&ssPageName=STRK%3AMEBIDX%3AIT

any good? or junk?

[raygdunn]

If it's been built wrong, then all bets are off. Was just pointing out that this is not a nice way to treat logic ICs. It's an old schematic and it was most likely a noticeable saving in parts and assembly to omit voltage underswing protection. Low current outputs are a blessing in this sense.

Where was the scope common connected in the above picture, raydgunn?

Clipped to the protection diode on B+. I'm using the "median" setting on both signals to improve the vertical positioning, so one can't directly compare the signals. But I'm guessing that is a usual setting.

Ray

[ODM]

If it's been built wrong, then all bets are off. Was just pointing out that this is not a nice way to treat logic ICs. It's an old schematic and it was most likely a noticeable saving in parts and assembly to omit voltage underswing protection. Low current outputs are a blessing in this sense.

Where was the scope common connected in the above picture, raydgunn?

[FatBob]

Ok but is it right to connect the timing resistors to +5 with the chip at Gnd and -5V?

[Qiaozhi]

I'm not sure which version of the Baracuda schematic you are all looking at, but it would appear that the CD40106 should have its VCC pin connected to GND, and its VSS pin connected to -5V.
The reason being that the 2N5485 sample gates are N-channel JFETs. This means that when the JFET is conducting (on) the gate has 0V applied, and is off when the gate is in reverse bias (i.e. at -5V).
Basically, the original circuit looks ok to me.

[FatBob]

Well I do not wish to argue here. I just want to say if you put a resistor to 10V between 2 caps the voltage (between the caps) will rise to 10v.



The power pin of the 40106 must be at the highest potential of the circuit (IE 20v , +5V).

I believe this is the way it should have been done;

[kt315]

max rating for cd4000b series is 20v. in 40106 -internal.gif the input connected NOT directly to +10v
but via a resistor. sometimes people do not want see evident things.

[FatBob]

I agree it is per the original board and assume the original works fine (as they were sold for a long time).

I just wonder if the 40106 should be powered off +-5V instead of Gnd 5V.

Here is the Whites 1000 which also uses a CMOS inverter and it is powered from +- 5V;



These CMOS inverters are sometimes used in unorthodox ways as they are an array of FETs internally.
I was hoping an engineer would step in and say which way was more correct.



This is how our circuit would look;


The data sheet says input can be Gnd to Vdd (5V in this case), it doesn't say what happens when we exceed that....

[kt315]

If your timing resistor ties to +5V you will be outside the chips reference of -5 to 0.

CMOS chips do not like that.

So maybe that's why the latchup would occur?

guys, i again must notice for you - original Bara works fine.
all problems you tell about are ONLY YOUR problems. NOT of the original schematic and of the original PCB.
you do something wrong and people are thinking that Bara has problems. NOT!
i especially copied original PCB and did see no one problem.

[FatBob]

If your timing resistor ties to +5V you will be outside the chips reference of -5 to 0.

CMOS chips do not like that.

So maybe that's why the latchup would occur?

[kt315]

important issue.

7660CPAZ = 10 V
7660SCPAZ = 12 V

[kt315]

important issue.

I've noticed a few people here are having problems with the 7660.
You need be aware that there are two versions of this IC - the 7660 and the 7660A.
The 7660 performs supply voltage conversions from positive to negative for the input range of +1.5V to +10V, and the 7660A has an input range of +1.5V to +12V.
The maximum supply voltages are also:
7660 = +10.5V
7660A = +13.0V

[kt315]

It shows a 5V supply for the 40106 but some of the timing resistors tie to 5V above
the positive pin!
--
yup. and what??? you want to say that is wrong?