Simple Simon Slave power control, The other "SSS"... Options

[212]

Waiting for someone smart to do this was boring, so I'm messing with it myself.

What I have so far is a simple 555 circuit set-up for around a 10 second cycle time... driving a relay. I found a positive signal on the real SSS that will trigger an inverter to change it to negative, to start the 555 timing cycle.

The idea is to have this control slave flash power, to conserve battery life. One that can be made using parts readily available from Radio Shack.

By adding a sensor( the name escapes me) it will only charge in the daytime too. This is working so far, but I need to draw a schematic for it that makes it neater looking than it is so far.

The 555 I have says it works from 0-70 degrees Centigrade, so I need to see what happens when it gets colder. It may not work at all???

If this pans out, I think it can be used with most camera control boards, including the old MS-20 and 425's, we will see. This is officially in "public domain"

Any input or suggestions would be appreciated

:hags:

[212]

O-yea, the cam control board will refresh the slave when it refreshes the camera too.

This is something Brian did with his BG1 controller. It works so well I wanted to use it with other boards, hope that is OK Brian

[212]

I have a better idea... maybe...i'm going to try to use a 556 duel timer to also refresh the flash without the controller doing it

Wish me luck...less errors

[Jon5ja]

A 555 timer is going to pull WAAAYYYY too much power to save you any :-)

Your concept will work, though, at least to the degree of keeping the flash unit ready to fire. It wouldn't be very near optimal, but would beat the heck out of leaving the flash on all the time. The main reason you can't make it optimal is that the capacitor characteristics are very bad right after a flash, and gradually get better as you keep bumping it up. If you bump it too far, though, you just wasted all that extra energy because it'll drain right back down to where you would've liked to stop anyway, ha.

I'd use a CMOS inverter with a Schmitt trigger input (like a 74C14, or you could use a CD4093 and tie one input of the NAND gate high and use the one input and the output as an inverter). Also, use a MOSFET to switch the flash instead of the relay. I'll draw you a pic tomorrow, my wife says I can't stay up past midnight tonight.

You could also have the second timing circuit (basically another inverter or gate, and a couple resistors and a capacitor) and make it turn on the flash unit long enough to completely recharge after a pic was taken; then, the refresh "ON" time of the other circuit could be much shorter.

Jon

[CoyoteBandit]

This would be great, I would love to see a simple schematic for doing this, I haven't etched any boards for awhile!

[genhob]

Chis & Jon - I hope you guys can figure it out. We could really use an option for slave controller.

CB - Taking pre-orders? ;-)

[Jon5ja]

212,

I hope I didn't offend you with my reply last night... I reread it this morning and realized it might have come off a little abrupt -- I was still adrenaline-filled from watching the Texas-USC game, ha. Of course, even with the current draw of 555's, it would be better than the full draw of the flash unit.

This circuit will draw only a handful of microamps instead of the milliamps that a 555 circuit would draw. Here's a little schematic that should do what you were talking about. The trigger input is set up to be taken low (to ground) when a picture is taken to cause the flash unit to recharge. If you need to trigger the recharge when taken high instead of low, the unused gate could be inserted between the trigger protection stuff (D3,D4) and pin 8 of the chip.

It really looks more complicated than it is, since it's a recharge timer (R1, R2, D1, C1) and the associated gates as well as a refresh oscillator (R3,R4,C2,D2).

I haven't built the circuit yet, but nominal calculations were for a refresh of 1 second duration (timed by R3 and C2) repeating about every 2.5 minutes (timed by R4 and C2).

The recharge timer that gets activated whenever a picture is taken is nominally set for 15 seconds (timed by C1 and R2).

You can change either the resistor value or the capacitor value to alter the times. Doubling a resistance (or a capacitance) roughly doubles the time. Of course, if you change C2, it will affect both the refresh interval and duration.

D3, D4, and R6 are input protection for the chip. If you were ABSOLUTELY POSITIVELY SURE that the input would stay between ground and +V, you could leave them out (but I wouldn't).

[Jon5ja]

I re-read Chris's first post and see that he had to invert the trigger signal to get it to negative... so... here's the schematic modified to accept a positive trigger as described above:

[hags]

Man.....I wish I could do that.....awesome schematics Jon....

hags

[Vic]

Nice work guys-keep it up :yes: :flag:

[Trapp]

[212]

WOW Jon5ja :cool:

See there, all it takes is to ask and someone will feel sorry for me and help. I'm going to study the post better but I wanted to first thank you for the help. And of course you did not offend me at all.

[treetop]

That is something I am out of my league 212 looks like you have some work to do building a few of these Jon5ja

[Jon5ja]

Well, I breadboarded the circuit this evening... here are a few observations (using 4 NiMH cells, 5.3 volts):

1.) CMOS is easily killed by static. I knew that, was careful, and still killed the first chip before I got it breadboarded. Use a grounded antistatic wrist strap and mat.

2.) You can't just leave that "TRIGGER" input floating or it does bad things. I forgot to connect it at first and its behavior confused me. If you don't have it hooked to a logic circuit on the camera control board, use a 1M resistor between it and ground to give it a "default" value.

3.) Had to reduce R3 to 15K to get a 1-second "ON" time for the refresh. With the 2.2M still at R4 and C2 measuring 103 uF, I got an interval of 122 seconds. Close enough.

4.) Recharge time was 22 seconds with the 2.2M at R2 and 10 uF at C1. I reduced C1 to 4.7 uF (measured 4.8 uF) to get the recharge time down to about 10 seconds.

5.) The odd one: I failed to anticipate that when the "recharge" cycle was activated, holding pin 5 low for 10 seconds, and consequently holding pin 4 high for 10 seconds, was going to charge C2 up almost to battery voltage. In normal oscillation, C2 goes up and down between about 1/3 of V+ and 2/3 of V+. Charging it all the way up during the "recharge" caused the first refresh cycle afterward to be almost 3.5 minutes, compared to 2 minutes in the normal case. I can leave it alone (probably not that big a deal) or I can fix it with 2 or 3 more components. I actually did fix it on the breadboard, but I feel like it's a kludge, so I'm still thinking about it.

I've got it on a flash unit now so I'll let it run a few days and see what it does.

Jon

[flintlocker]

Well, I breadboarded the circuit this evening...

Can't you just see him being sucked back in.....