Problem with homebuilt Servodriver Status Board

[RotorRouter]

I have just built a controller that has 4 Gecko G320 servodrives. The fault LEDs have been wired and located on the case as shown in the Gecko specifications. I have wired the LEDs so that one Momentary Center Off switch can (theoretically) engage / disengage the servodrives. My knowledge of electronic is extremely limited and it appears that my 'gang' wiring of this switch is not providing the +5VDC required for 5 seconds to remove the Error state.

The following is the wiring of the Servodrive Status Board. Could someone point out where the schematic is wrong?

Thanks.

System did not accept revised drawing, so I will try and put it seperately in the following post.

[RotorRouter]

Drawing for above posting;

[fkaCarel]

There are no current limiting resistors on the bases of the transistors. You combine the driving of the error leds with outputting signals. Through the load of the Led's your 1-signal will not go over 1 volt. So it won't work. You have logic on the right side, now put it also on the left side and drive the led's separately.

Carel

[RotorRouter]

FkaCarel,

Thank you for your help. Unfortunately, my knowledge of electronics is obviously limited.

I have provided a separate +5V line to the LEDs and another to the Emitters connected to the [Engage] momentary contact. In addition, I have put resistors between the [Engage] and the [Disengage] lines and +5V to try and draw each line high when the momentary contact switch is not connected to that line. Neither works.

When you mention the current limiting resistors on the bases of the transistors are you referring to the LED activating transistors or to the momentary contact switch transistors?

Or, if you would be willing to say what you previously said but in a slightly different way, I may be able to combine your two posts and then understand the solution.

Thanks again.

Dave

[fkaCarel]

A transistor is an amplifier. So you need a small current on the basis to get a greater current to flow from collector to emitter. This is the current limiter, normally 4k7-10k. Then for a rigid design you have to predefine the states of the inputs. Your inputs are "floating". If the switches are open there is no determined state of "0" or "1". Use longer wires and your circuit will dance with your local radiostation. You use the middle of the totempole (the two serially connected transistors) to drive your status led transistor AND your logic (4-port NAND with inverting inputs?). The transistor loaded with the loads takes care of the fact that the voltage on this line can never reach a logical "1". The load is to heavy. I have not the faintest idea what you try to achieve with this circuit, I can only see that it does'nt work. It looks like you want the circuit to maintain a state after you toggled a switch. So put your cards on the table and let's see how we can help.

Carel

[RotorRouter]

FkaCarel,

It looks like you want the circuit to maintain a state after you toggled a switch.

Yes. This circuit is to function as an ERROR output and as a RESET input.

The circuit shown above is to be a portion of the total controller circuit for 4 to 6 Gecko G320 servodrives. The bottom of page 4 of the Gecko manual http://www.geckodrive.com/photos/G320_REV-4_MANUAL.pdf [(TERM. 5) ERR /RES] shows this 'optional external fault LED circuit' portion of the required circuit for just a single servodrive.

I am trying to keep the separate external LEDs for each servodrive (as is shown in the manual), but, use 1 common Momentary Center Off toggle switch to start and to stop all the servodrives.

I assume that it should be easy to have 1 common Momentary Center Off toggle switch activate 6 ultra miniature Sanyou relays and these relays would replace the toggle switch in the 6 Gecko circuits. It just seem that the use of an all electronic circuit would be more efficient.


Thanks.
Dave

[fkaCarel]

Due to a crash, no acrobat reader available at the moment. First advice: if you want to start a multiple circuit, start with a single and build from there. Same applies for family's. Second: in electronics a relay for signals is a loser's option. One cannot sink deeper. For a presetable and resetable, state maintaining chip look at 74LS74. 2 in 1 package. Keep it simple: wire the inputs together and use 1 output for logic and 1 for Led-driving. Dual NAND: 74LS20, 6-pack inverters: 74LS04.

Carel

[RotorRouter]

fakCarel,

Thank you very much for your help in working through this problem. I will remove all the transistors except for the ones on the LED lines.


Dave