Simple timing circuit, 3 x 15Hz = 45Hz

[crutschow]

You need to apply the rated voltage to the solenoids and measure the current draw with an ammeter. That will tell you what type of driver circuit you will need. The 4017s will only drive a few tens of milliamps which is likely far less than the solenoids require. Or is there some type of driver circuit already with the solenoid?

 

[colin55]

Measure the coil resistance with an ohm meter.

We are assuming they are rated at 10v -12v operation.

 

[Cobalt60]

I'll bring a solenoid into work on Monday. I'll be able to measure its resistance and current draw then. BTW the travel on these solenoids is only about 1mm.

 

[Cobalt60]

OK so I brought a solenoid to work today. I measured the resistance through the 2 wires and came up with 0.8ohm, does that sound about right? Is that enough information to find out what sort of driver circuit this needs?

I tried measuring the amp draw, but my power supply kept maxing out at like 3.9A. These solenoids can supposedly operate about 10000 times, at a rate of 15Hz, on a regular 9V battery. Assuming each cycle lasts for 1/30s, a typical 9V is 500mAh, and my math is proper, I figure these solenoids are actually drawing about 5A. Does this sound about right to you guys? They did appear to operate properly though even when I limited my power supply to about 2.5A

Well, if we have the specs on these solenoids figured out pretty well, then lets start talking about the driver circuit!

Thanks

-Chris P

 

[colin55]

The next thing you have to do is work out if the solenoid will operate on 9v, 6v, 5v, 4v, 3v.

 

[Cobalt60]

Ok so bring it back to work and try it with these various voltages (keep in mind my bench supply doesnt hit 4A)? What knowledge will be gained by trying the solenoid at lower voltages?

 

[colin55]

You really need to know if the solenoid is designed for 9v, 6v or 5v as the resistance is very low and you will have great difficulty in supplying a high current. And it may not be necessary.

 

[Cobalt60]

The solenoid was sold with a product running off a 9V battery. And the 10V 6800uF cap was also included. But maybe the solenoid itself was designed to run off a range of voltages, say 6V -> 10V?

Well anyway I may as well try the different voltages and see what the results are.

 

[crutschow]

Certainly a 9V dry cell battery can not deliver amps of current.

 

[colin55]

If the coil resistance is 0.8 ohm, the current taken by the solenoid and the heat generated will be considerable if it is connected for any length of time.
That's why the original circuit may have dumped the energy from the 6800u into the coil. What type of transistor or FET was connected to the coil and to the 6800u?

 

[Cobalt60]

The 10V 6800uF caps negative is connected to the negative of a 9V battery. The positive is connected to a 2 pin IC, labeled S14, which in turn is connected to an 8 pin surface mount IC labeled ND5 8410A.

Im not sure exactly what each pins number is (on the ND5), but I will guess. And I cant say where some of the traces go since I cant see the middle layer of the PCB. But what I do know is pins 1-3 share a trace, pin 4 has its own trace, the S14 IC is soldered to pin 5 and 6, and it looks like pin 7 and 8 share a trace that goes to one of the pins of the solenoid. However, I cant tell if pins 5/6 are on the same trace as 7/8.

Also, I brought the solenoid to work today and tried various lower voltages. The solenoid operated at very low voltages (I think it worked at like 2 or 3V), but with each decrease in voltage came a noticeable decrease in power. However, it did still seem quite powerful at 5V, but I dont feel that my perception of its power at 5V is proof that this solenoid actually operated at that voltage originally.

 

[colin55]

Now look at the traces (the track-work) on the PC board.

Look for very thick tracks. Since we have absolutely no idea how the solenoid is activated, we look at thick tracks and see if the chip is actually a power device that delivers CURRENT to the solenoid.

It seems to me that the chip charges the capacitor (slowly) and dumps the energy to the solenoid and this will need very thick tracks to prevent energy losses or burnt out tracks.

 

[Cobalt60]

After having done some research, I see that Digikey sells a part, mfg part # SI8410AB-C-IS. It is a SOIC8 package, the same as the IC that the solenoid and 10V 6800uF cap are connected to. The 8410A is an IC isolator 1CH 5.5V. Not sure exactly what that means, but it does suggest to me that the solenoid was possibly operating at 5.5V in its original application.

 

[Roff]

After having done some research, I see that Digikey sells a part, mfg part # SI8410AB-C-IS. It is a SOIC8 package, the same as the IC that the solenoid and 10V 6800uF cap are connected to. The 8410A is an IC isolator 1CH 5.5V. Not sure exactly what that means, but it does suggest to me that the solenoid was possibly operating at 5.5V in its original application.

You seem to be implying that all ICs in an SOIC8 package run on 5.5V. Or did I miss your point entirely?

 

[Cobalt60]

As far as thick traces coming out of the IC, the trace that pins 1 - 3 share is a thick trace, but I cant see where that trace goes and it may even just be a jumper. Pins 7 and 8 have a thick trace which goes to one of the pins of the solenoid.

 

[colin55]

Are you sure S14 has only 2 pins.

 

[Cobalt60]

Are you familiar with the term "non sequitur"?
You seem to be implying that all ICs in an SOIC8 package run on 5.5V. Or did I miss your point entirely?

You must have missed my point. My point is, the IC, which is currently connected to both the solenoid and the 10V 6800uF cap, is called an 8410A. The 8410A is a 1CH 5.5V IC isolator.

My reference to it being a SOIC8 was merely to suggest that I have identified the IC (my board has a ND5 8410A SOIC8, Digikey sells a SI8410AB SOIC8, I think it is relatively safe to assume these are both the same device, or at least very similar).

Now, I dont know what a 1ch 5.5V IC isolator is, but I am assuming, since it is connected directly to the solenoid, that it is highly likely that the solenoid was receiving 5.5V, whereas I previously had thought the solenoid was operated on 9V.

 

[Cobalt60]

Now that you mention it S14 appears as though it could be an SOIC4 device, but there is solder on each end so I cant see the pins. So if it is 4 pin, the pins on each side are bridged together. But it looks to be about exactly half the size of the other SOIC8 chip.

 

[colin55]

The data sheet for 8410A shows the chip is only capable of delivering about 10mA so it doesn't look like the IC delivers current to the solenoid.

Work out the path from the 6800u to the solenoid.

 

[Cobalt60]

According to the data sheet I am looking at the 8410A is capable of 10.8A continuous and a lot more when pulsed:

NDS8410A pdf, NDS8410A description, NDS8410A datasheets, NDS8410A view ::: ALLDATASHEET :::

Im assuming I misidentified it the first time.