Silver Sabre 2 schematic

[Merc]

Here is a schematic I've had for some time but I wanted to check it out good before posting. Let me know if you find any errors.

Merc

[Unregistered]

Nice schema, Thanks !

Bat check +5 = -5 ? near tant. 10 uF

[porkluvr]

Nice schema, Thanks !

Bat check +5 = -5 ? near tant. 10 uF

Very observant!

Merc, would you mind if I hack your diagram and possibly post pieces of it in other threads? I will give you proper credit and make links to this thread.
thx

[Merc]

Silver Sabre II Schematic

I don't mine. If a change needs to be made, I don't mind making it and re-posting. Is the battery check circuit wrong? I will need to take mine back apart to check.

Merc

[porkluvr]

Batt Check and -5V

Hello Merc-

Don't bother to disassemble. If your diagram is changed to show -5V, Battery Check will agree with Bandito, Golden Sabre, and Lobo circuits posted elsewhere.

https://www.geotech1.com/thuntings/f...splay.php?f=18

The 470k portion of the RC network (470kΩ & 10uf) would be shorted by the diode if anode is connected to positive voltage. (Sometimes quicker and easier to explain what doesn't work, than to explain what does!) Know what I mean?

I have a SS2 "MicroMax"(?) that is different from what's in your schematic, but your schematic covers my GEB and DISC sections better than SS+ schematic I have.

Thank you, thank you!

[Merc]

Correct Silver Sabre 2

porkluvr,
You were absolutely right about the battery check circuit. I had to know for sure so I took mine apart and measured the voltage at the anode of the diode. Sure enough, -5V (-4.83). I have corrected and here is Rev 2 of the schematic. I am sorry that happened. I realize how frustrating it can be to try and build something buy a wrong schematic so I'm grateful to all for pointing that out. If you spot anything else, let me know.

thanks,
Merc

P.S.
I'm working on my Toltec 100 schematic in my spare time and hope to get there eventually.

[TXP]

Hi,
Battery check is not so important, but connection of power supply for oscilator is not correct. This type of oscilator has amplitude stabilisator and you can put it direct on battery voltage for more transmit power.

[porkluvr]

no free lunch

Hello again,
Merc thanks again for the scat. If you get the Toltec drawn up, great - but nobody can fault you if you don't.

TXP - I wish you were right but your modification idea may not be so straight-forward as it would seem. The FET gate circuit could be a source of amplitude instability if not tailored correctly.

The top trace shows iL1 nice and stable. This uses the "original" SS2 values as shown in Merc's schematic.The middle trace shows iL2 hunting for equilibrium. The two circuits are the same except for a 7V supply voltage for oscillator 2.

I played with the RC network to obtain amplitude stability in oscillator #3. Notice the hugely different RC values. On close inspection, see that oscillator #3 amplitude is not really stable, but is quivering.
1.2nF, instead of 1.3nF could make the difference. I derived the circuit empirically - through trial and error. I have no formula to make things work.

I know this is only a computer simulation but it is cause to be wary. You don't get something for nothing. As a disclaimer, or to add to the confusion: Golden Sabre and Eldorado circuits, operating at 14kHz and 10kHz, respectively, both exhibit the same anomalous behavior shown in the middle trace when I simulate them with component values supplied with reverse engineered schematics from this website.

I'm not saying this is what will happen, I am showing what could happen. I guess it could be said that computer simulation is a poor substitute for the real thing, but until I can set up an oscilloscope - it's all I got, and I'm being wary.

[Merc]

Silver Sabre 2

As far as I can tell, the oscillator is similar to the one used in the Eldorado. Are you sure it is not correct?

[porkluvr]

You're OK

As far as I can tell, the oscillator is similar to the one used in the Eldorado. Are you sure it is not correct?

Merc, Your schematic looks fine. I was showing what might happen when somebody tries to get more power out of Tesoro's "oscillator with FET amplitude stabilization" by connecting directly to the battery, but neglects to make corrections to the FET circuit. It makes sense when I think about it, but I can't define the behavior.

What's really confusing, and I wish I had a real lab: when I simulate Eldorado and Golden Sabre - I must make changes. All other things being the same, I cannot successfully use the same FET gate RC values shown on those schematics and obtain an amplitude stable signal. There is probably some unknown quantity at work in the real world that I am unaware of, (obviously, but I mean, besides the ones that I can IGNORE) not being represented in my spice circuit, and it's trouble in my virtual lab. So, I change the RC value and flip the switch again to move on. Inaccurate maybe, but fast.

In contrast, when I simulate your circuit, it works fine in original form. Smooth as a baby's behind. However, and as should be expected, when I raise VCC to or above 5.8V (as would happen with TXP's suggestion) amplitude goes crazy. The middle trace in my LTspice screenshot shows your SS2 but with VCC=7V instead of VCC=5V. Simulations suck, but there it is.
I'll go soak my head now.

[Merc]

Actually porkluvr, I was responding to TXP in the post before you.
By the way, you mentioned using part of my SS2 schematic. I can send it to you in the original QuickCad format or .dxf if that would be easier.

Merc

[Qiaozhi]

Hello again,
Merc thanks again for the scat. If you get the Toltec drawn up, great - but nobody can fault you if you don't.

TXP - I wish you were right but your modification idea may not be so straight-forward as it would seem. The FET gate circuit could be a source of amplitude instability if not tailored correctly.

The top trace shows iL1 nice and stable. This uses the "original" SS2 values as shown in Merc's schematic.The middle trace shows iL2 hunting for equilibrium. The two circuits are the same except for a 7V supply voltage for oscillator 2.

I played with the RC network to obtain amplitude stability in oscillator #3. Notice the hugely different RC values. On close inspection, see that oscillator #3 amplitude is not really stable, but is quivering.
1.2nF, instead of 1.3nF could make the difference. I derived the circuit empirically - through trial and error. I have no formula to make things work.

I know this is only a computer simulation but it is cause to be wary. You don't get something for nothing. As a disclaimer, or to add to the confusion: Golden Sabre and Eldorado circuits, operating at 14kHz and 10kHz, respectively, both exhibit the same anomalous behavior shown in the middle trace when I simulate them with component values supplied with reverse engineered schematics from this website.

I'm not saying this is what will happen, I am showing what could happen. I guess it could be said that computer simulation is a poor substitute for the real thing, but until I can set up an oscilloscope - it's all I got, and I'm being wary.

Hi porkluvr,

One thing that can upset SPICE when simulating an autonomous circuit, is the ideal nature of the inductor. Have you tried inserting a resistor in series with the coil to include the DC resistance?
You'll probably find that this has quite a large effect on the operation of the circuit.
I'll try this myself sometime this weekend. Too tired at the moment...

[porkluvr]

cable effect?

Well, Qiaozhi, everybody,

It's embarrasing to have to admit I made a mistake, but adding parallel resistance (in addition to the 22Ω series resistance and 987 pf capacitance I already had) will make the Golden Sabre and Eldorado oscillator circuits simulate without exhibiting horrendous amplitude instability. I see that cable RCL between search head and transistor should be figured in.

My models are vastly over-simplified fakes and sometimes it really shows.

So, what this suggests, is that there might not be such a horrible price to pay for tapping directly off the 9V battery for the transmitter... .

My SS2 detctor doesn't use FETs (not even in the signal channels) so I had better leave this to be sorted by somebody else. I really apologize for having thrown a firecracker without looking first!

[Duncan]

IC power supply pins?


Hi Merc,
I have been looking at your excellent schematic of the Silver Sabre II,
but I do not see any power supply connections shown on the IC's,
LM353, LM393, LF442, and LM358.
Do these require +5 and -5 volts or +9v and ground, or what?
Are there any additional rail decoupling capacitors placed directly across these IC power supply pins?
I would be most grateful if you could provide this information.

Best regards

Duncan

[Duncan]

Zener Diode?



Hi Merc,
Please can you tell me what the voltage is of zener diode 1N5229 (in transmit circuit) ?
I just checked the datasheet for this diode and this type number
covers a vast range of different voltages.

Best wishes

Duncan