Thing to do is get an MSP-430.  Put a transistor for your solenoid on the line with the red led, as the native app is 'blink the led'  Use a to220 n-mosfet with a Vgs-th value of about a volt-and-a-half.  You will need to shunt your load with a backwards diode for anti-spike.  A little gold-doped or shottky thing would probably work here. We need to wait for the diode to turn on, so we want low capacitance, next low threshold.  I would get this all working preliminarily on a launch pad.  Then get their RF kit.  The great thing about TI is that they take your calls and will keep taking their calls, so if you run into any speed bumps, I would keep callin'.

  Thanks for your time Don......Sounds like the MSP-430 is a board I can start to plug things into so I can test how the components work and see if they meet my needs. Unfortunately for me most of the other items and remarks I will need to research and look up. Most of what you are telling me is over my head due to the zero experience I have in this field. Do you think it would be a good idea to hire someone to design this for me....and if so could you recommend someone. Again, thanks Don

Don't worry about my time, I am dithering in anticipation an in-depth look at STM32 RTOS-es and am seeking anything simpler to abey me while I settle down to this winter-time task.  What makes the MSP430 kinda fun for me is that it codes in C+ (without an RTOS layer, typically) so  and I can simply mangle the examples into shape.  The canonical app for the MSP-430 RF kit, IIRC, is an interrupt driven networked temperature (on board sensors) so I don't think there is a world of difference (obviously superficially) here.  Let me run through some typical questions:  Are there off-the-shelf solns?  Do we need a digital computer?  How intelligent are the entities you are (presumably) defending against.  The analog guys have a pretty decent off-the-shelfer originally motivated by RF car keys.  This prevents spoofing the transmission because the lock sends an encoded key for the next opening to the physical key.  Early implementations were vulnerable, but I think they have tightened up their acts recently.  'Wireless' doesn't necessarily imply RF.  Any modulable form of energy could be used, hypothetically.  How about ultrasound? 

If you need a designer, I am available, though not cheap.  My practical weakness here is that I have not attended the RF schemas typically used nowadays to the extent I would like.  This would slow me down a coupla weeks, so if your horizon is short, I would find someone better versed in this.

Really, to comment more intelligently, I would need to know more.  How valuable is that which you are protecting?  How big/hazardous?  Remember, secrecy and guile typically yield better results then strength alone.

If I was terse before, let me start again.  One complication in electronics is that there are two load parameters: Resistive(Re) and reactive(Im).  Resistance, except in the world of op-amp filters and gyrators is typically a positive number.  Positive (imaginaries) reactance implies 'inductor' or 'coil,' negative 'capacitor.'  This contrasts with mechanical reactance, which is a single-parameter joint typically called 'inertia.'  Resistors are (typically) IR lightbulbs, they act like a frictive element.  Reactors store energy, almost invariably to return it later.  The exception would be some EMP devices.  Inductors (what you got) would store energy in the magnetic field, capacitors in the charge field.  Capacitors are, typically, profoundly more volumetrically efficient than similarly-sized coils, making them more popular.  For the physics wonks in the audience, I feel I must note the symmetry breakdown:  Inductors exhibit induction, so we can make things like transformers and transductors with them.  Caps, not so much.  Anyway, your load is +Re,+ Im.  If you turn on a fan, get it up to speed, then unplug it, you will likely see a spark.  This is an inductive load.  If you plug in an old, large analog stereo amplifier, you will see a spark when you plug it in.  This is a capacitive load.

So your load has a resistive term, the resistance of the wire in the coil.  This wire is long and thin, so R is non-trivial.  In shunt with this load, is an inductance.  Without gettin' too wonkish, there is the natural free-range inductance of your coil, + a larger, less-well behaved inductance caused by the insertion of the (probably ferrite) slug that makes the solenoid.  Electromagnets typically don't have great reach, as the force diminishes as the square of distance, so without a linear motor, rotary motor + mechanics, or fluidics, you cannot move stuff very far this way.

Anyway, this shunting inductance diminishes in influence the longer we energize, its a logarithm thing, so it never ends except that our universe ain't made so much out of continuous stuff.  We have a duration that is when 0.68 of the final value (here current, capacitors potential) is reached.  We call this value a time-constant which we typically measure in seconds.  Now, there is a subsequent moment when we attempt to shut off this load.  Your powerQ is probably a (greater than an ampere-and-half static rating) MOSFET.  These moieties, especially, like all transistors, would probably prefer to operate in a class-D or saturation mode.  If they are off, our Qdiss is low because we have little current, if they are on, we have little potential difference across our conduction channel.  Remember Power (Watts) = Potential difference (Volts) * Current (Amperes).  So ya' turn off the power device quickly.  This leaves our magnetic field in place.  It collapses.  It induces an instantaneous potential of a magnitude great enough (for practical purposes, physics wonks) to maintain the current in our conduction channel.  Its total energy is the 'area under the curve' we provided to get things going.

Fortunately, your load does not require a 'soft landing.'  Certain stepper motor drives (and stepper motor situs) and large solenoid-operated valves require a complex clamping scheme.  You almost certainly don't.  What you need is to shunt the load with a diode that seems 'backwards.'  This sort of clamp is of no avail across the switch, one is there anyway.  Bipolar stepper drives that are really tiny use this diode, but the surge in QA is quenched by by QA' and vice-versa, through auto-transformer action. I digress.   Alternately, we could quench with a Zobel network, passive and fast, but we might be ringing into November.  Hybrid solns are possible and work great, model them in Spice. How do we rate our Q and D?  Max current is set by the purely resistive model of our load and is thus inferable from Ohm's law.  Remember to derate!  Breakdown potential is supply potential, remember to derate, plus spike voltage, which is largely dependent on the capacitive reactance of our diode.  Derate, derate, derate!  Don't go crazy-high though, as the way the manufactures achieve (presuming like technology) is to reduce the conductivity of the bulk conductivity by doping less.  Practically speaking, if your potentials are low enough, you can use Shottky diodes.  At higher potentials, I would employ UF (ultra-fast) diodes.

So what happens if I don't clamp?  Maybe nothing.  Typically, though, hot electrons will poke little holes in my power switch and it will degrade over time.  I knew some guys in a machine shop in the eighties who thought their stepper-motors were wearing out (not too likely) it was probably their drivers power Qs.

==========

Wanna play a philosophical game?  Propose imaginary terms for real values.  For example one possible imaginary term for the for a commodities' value is: fungibility.  I digress.

Hi Keith, Your idea is good. You can switch the Solenoid using a MOSFET/Relay or Some PWM Driver like DRV102 from TI. To control the solenoid relay wireless you need to have a controller like MSP430, ATmel Atmega8 or anything you are familiar with and the wireless part will have either a IR receiver (TSSOP kind of thing) and a General IR Remote or if you want to control it from your Android have a look at www.ectech.in/projects.htm

  Wow......thanks guy's ..I am finding out quickly that I am in over my head. I have invited a person who I believe knows a few things about dc voltage and how solenoids work and may have some knowledge about wireless. I will show him your very helpful replies. Looks like this is when I start my journey into the electronics field.........looks like it may be a long journey. Thank you for your help. I will let you know of any progress, and if successful I will post the results of what I believe will be a great idea.  Thank you

Typically, to energize a moderate load in a single-ended manner, like on-off we can use an N-channel mosfet.  Since we have our choice of P or N, and since, in Si, N is perkier than P as a charge-carrier, we go N thus finding ourselves pulling down to activate our load.  This is a three-terminal enhancement-mode device.  There is a main conduction channel.  Drain in our Nchan is the topside connection of the channel, Source is the lower end, typically connected to the bottom of a unipolar voltage supply.  Typically it goes: top-of-supply -> top-of-load -> bottom of load -> drain | source -> bottom of supply.  The third terminal of the mosfet is the gate, which modulates the conductivity of the channel.  I should mention that there is a backward diode in shunt with the main conduction channel, just hangin' about.  These devices are just ok in a linear mode, as an aside pos tempco.  Where they shine is switchmode.  Bringing the gate (gate potential relative to drain potential) above Vgs-th, (as a practical manner with some margin) and our channel is enhanced so as to be conductive as the bulk Si.electrically connecting Drain and Source, save Ron.  Breakdown voltage of the channel is a critical param, and comes with the cost of higher Ron.  Slewing the gate to ground turns the channel quite off.  The gate is rather capacitive, so at frequencies associated with SMPS, we need buffers to dump the gate charge quickly.  But for any likely frequency useful in a device such as a solenoid, we don't have to worry about gate-charge too much.  If our load is purely resistive, BV doesn't have to be much greater than supply potential.  For inductive loads, typically some kind of snubbing is required to minimize kickback spikes, and more margin in terms of BV is wise.  Modeling in SPICE works great here, but drag out the o-scope for final conformance verification.  For capacitive loads or thermally reactive loads, inrush limiting should be considered.

An excellent driver for a typical Mosfet would be a TLP351 saturating opto-isolator with CMOS output.  7/800 Ampere into the input led drives the output high.  Were this attach to the gate of a typical (mind gate BV) mosfet the conduction channel would go to a low-Z state.  The nature of the output structure of this iso makes for quick transitions both on-off and off-on.  In the SMPS situation one might insert a preamp:  Tiny NPN collector tied high, tiny PNP collector tied low.  Emitters bussed as output to gate of mosfet, bases bussed as input and attached to optoisolator output.

To compute the 8.75 mA for the input diode, first making sure that one's CV doesn't need a buffer, noting we have both ends of the diode so we can pull up or pull down as we please, lets guess the input diode drop is 1.2V, and, say, a 3.3 V supply gives me a 1.1 drop across my ballast R presuming an ideal logic driver to the left.  V=IR, so R=V/I, 1.1/8.75/K ~ 125 Ohms.

If you ever use the Ham technique of putting sub-circuits on boards to be connected to other little little boards, such fun since those little screw-terminals came out, and you put a mosfet on a board to serve a governor to be determined later, insert a 50K 1/8W (or some such) between gate (control terminal) and source (reference terminal) so that the conduction channel is always off in the quiescent state.

No, 2.1V drop.  240 ohm resistor.  Now I can sleep!

You may wish to take a look at this which gives you an easy way to get what you want without programming, designing boards etc.

Image is for illustrative purposes only.
Please refer to product description

 

Manufacturer:

LPRS

Order Code:

2096230

Manufacturer Part No:

RSC2-ALIEN-E

Technical Data Sheet (2.44MB) EN