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I'm trying to get a cheap pull-type solenoid that can operate for at least ten seconds at a stretch to serve as an electronically-controlled ward in a lock (for a wooden box) I'm building.

I'm a novice and confused at my findings. Can anyone enlighten me?:

This model touts a stroke length of 0.05 inches. Does that really mean that the shaft only retracts 5 hundredths of an inch?

What's a "nominal" stroke? How is it different from a maximum stroke? (I'm looking at the table on this page.)

If max stroke is specified but nominal stroke is listed as n/a, does that mean that nominal stroke length is 0?

Lastly, any counsel on where to shop for the solenoid I need? I want a retraction of about 1/8 inch but could just as easily make use of 1/2 inch.

TMI: My shopping criteria:

  • cheap
  • small
  • >= 1/8" stroke length
  • DC
  • <= 12V
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If this is for the locking you could consider an R/C servo instead. A bit more complex to operate (you'll need a 555 chip or a uC), but uses a lot less current. – Wouter van Ooijen Jul 15 '12 at 7:07
If this is a door security deadbolt, it needs to be a rugged piston and mounting bracket. – Tony Stewart Jul 15 '12 at 19:06
Sorry to have not specified the type of lock. It's an integral lock to hold a hinged lid closed on a wooden box. – JellicleCat Jul 15 '12 at 20:56

2 Answers

up vote 3 down vote accepted

If it says the stroke length is .05 inches, then you have to assume the stroke length is .05 inches (50 mils). There is nothing ambiguous here.

The nominal versus maximum stroke is less clear. It appears they are rating the solenoid for pulling in the nominal amount, but are saying that it can actually start further out. That will likely mean significantly less starting force, though. They are saying that this solenoid is meant to be used so that it is held the nominal distance out, but that it can mechanically go further. However, it's hard to trust what they say when the starting force is labeled in Ohms. Huh? I'd seriously wonder what else is wrong with that datasheet. I'd find a different solenoid, preferably from a different manufacturer.

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I would try better specsheets from the OEM vendor rather than the brief version from this distributor. This looks like a good design of a "magnetic latching solenoid" check for catalog for door magnetic latches – Tony Stewart Jul 15 '12 at 16:01
The reason for Ω 1st is for 100% duty cycle P=R* I^2 and this can be used 100% at low current, low force or low duty cycle at high force. in the spec there is a table. of Amp-Turns force and current which are dependant on Resistance loss in windings for heat – Tony Stewart Jul 15 '12 at 16:08
actually any DC solenoid can be re-designed to be a magnetic latch, where power is zero and Ω is less important and mag.latch wont be cheap. so scrap that idea. Do you need the catalog or need someone to choose the part also to buy the part? and maybe pay for it too.. j/k :) – Tony Stewart Jul 15 '12 at 16:17
Component Selection criteria and priority of choices please? AC or DC, cheap or reliable? cost max? long throw or high force affects cost so minimize . LEDEX is listed for DC solenoids and Dormeyor for AC solenoids. Johnson Electric was started by Mr & Mrs Wang in 1956 making tiny motors and now is a supplier to automotive and camera industry >$1Bn/yr I think they will have your part. – Tony Stewart Jul 15 '12 at 16:34
+1 to Olin for info and brevity. Thanks also to Tony. I could use a recommendation for a catalogue that should supply the part that suits my task (I updated the details above), but if not, I'm comfortable returning to the search engines, now that I've got a little more understanding. – JellicleCat Jul 15 '12 at 21:05
up vote 1 down vote

Answers to your questions as follow;

Q Can anyone enlighten me?:

A Solenoids have high force vs displacement tradeoffs. Also higher the current, stronger the force but power dissipation is I- squared so duty cycle drops sharply with increased current, so you then operate at lower duty cycle. like 15 seconds ON 60 seconds OFF = 25% d.f.

Q 0.05 inches?

A Yes that is nominal. Max appears to be about 2x and you can get solenoids with 1.5" stroke in many sizes from same supplier, just choose best fit for your application.

Q "nominal" stroke?

A Shorter the stroke, the stronger the force. Longer strokes are permitted for ease of interface. enter image description here

Q where to shop for the solenoid I need?

A Go direct to OEM site (horse's mouth) for list of approved distributors.

Please see www.ledex.com (click on Stock Products tab) for our list of stock products available through our North American distributors.

In this case, Johnson Electric's appears to won both Ledex.com and Dormeyer .

You might be able to get a sample if you are a good customer.

Complete catalog below using DorMeyer brand , may be same as Ledex;

enter image description here

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Couldn't you just share a link with the pdf, instead of posting all those imagines? Or, if you have the pdf offline, upload it somewhere and post the link. – m.Alin Jul 15 '12 at 18:49
I would if I could but it was a php? download not a direct link. w2s.ledex.com/ledx/ds/LXEZR/LXEZR2e.lasso?pcode=L351 – Tony Stewart Jul 15 '12 at 19:03
+1 for the info. I'm not looking for bulk and have no history to make me a good customer, so I guess I need to look for a retailer who purveys these products. – JellicleCat Jul 15 '12 at 21:03

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