johndeverill

Hi Ante, Yup it worked OK connected to the PC. The circuit below is a bit simplistic but is colour coded as per the PC molex connectors.

Hi all, There is probably a very straightforward answer to this so you will have to excuse my ignorance. I have a PC fan controller that I want to run on batteries. It came with the standard 12v,-ve,-ve,5v molex connector. I connected the 12v wire to a 12v battery pack +ve. I then connected another wire from the +ve to a 5v regulator and onto the 5v wire. I then connected the 2 ground wires and the regulator ground to the battery pack -ve terminal. The LCD backlight comes on and that's it. I am going to be installing this in my car so should all ground connections go to the body earth of the car? If anyone can help with this it would be great as I'm sure it's a simple problem that I just don't have the knowledge to fix. Thanks in advance John

Hi Ed, That's great. Ill give it a try. Many Thanks John

Hi Ed, AFAIK it's the ISE4B PNP. Cheers John

Hi, Here's how it all connected

Hi, I have an SMC digital pressure switch. Basically it has three wires +,- and output. I want a 12v solenoid to activate upon reaching a set pressure. This is being used in a car. I connected it all up to the 12v battery. I then connected the output to a multimeter. All seemed fine, no signal in the output wire until the set pressure was reached and 12v was recorded in the output wire. Great, I thought. So I connected up a 12v DC solenoid....+ve to the output wire and -ve back to the battery terminal. Upon pressure being reached the switch threw up an overcurrent error that the troubleshooting guide says is due to a short circuit. So I tried with the multimeter again and all seemed OK. MM -ve connected to battery -ve. Am I missing something fundamental here? Do I need to connect the solenoid -ve to the body ground as opposed to the battery -ve? Thanks in advance John

Absolutely fantastic! :) Cheers guys John

Hi MP, That's great. At least I feel I am going in the right direction now. A transistor will have one conection with a varying voltage that acts to switch the circuit won't it? If so, would i then need to pass the differential output of the tranducer to an op-amp and connect that single output to the transistor? The circuit uses a pot. to vary at which point it switches. If the voltage ranges produced by the LDR and Transducer vary Iassume it would then be a case of varying the pot/associated resistor to get the switching range correct. Sorry without a circuit diag it is hard to really explain but if the logic is right I think I could get it to work with a bit of tinkering. Many Thanks John

Hi Guys, Many thanks for the info. I am very new to electronics so what I may be stating above may seem like a load of gobbledeegook, apologies. What i am trying to build is a pressure display/switch circuit. I have a LDR switch circuit currently and somehow was trying to replace the ldr with the pressure transducer so that it would switch dependent upon pressure rather than light. I think the circuit is using a transistor to switch as opposed to a op-amp. I also have a panel meter, which has differential inputs, so I assume would connect without a problem. The confusion I am having is getting my head around differential signals as I have seen transducers that output via one wire as opposed to +/-. Does this sound a feasable concept? Thanks John

Hi, Sorry PDF was too large to attach so I've attached some zipped images from it if of any help. Thanks John trans.zip

I have a trnasducer which outputs a 0-330mV +/- digital signal. I want to transform this to a 0-330mV analogue signal. Can I do this via an op-amp and can anyone give any advice on how to do this? Many Thanks John

Many thanks Alun, You have been a great help. Regards John

Hi Alun, Thanks for the confirmation. I suspected it would be nice and easy...for a change! I also want to convert the signal to a uni-polar signal aswell. Am I on the right track by thinking that you would connect the bi-polar to an op-amp? Many Thanks John

Hi, If you have a transducer with differential outputs can this be connected directly to a panel meter with a differential inputs to measure the output voltage of the transducer? Thanks in advance John

Hi, If anyone could help on this I would be eternally grateful as it is the last stage prior to my circuit being complete. Essentially I want the output signal/voltage of the tranducer to go to a panel meter. The transducer has a + and a - output connection and reads 330mV full scale output at 30psi. The panel meter has + and - input terminals. Can I just connect the + output of the transducer to the + input of the panel meter to read the voltage produced by the transducer on the panel meter LCD display? Many thanks John

Hi MP, Very true, it would make life a little easier. Transducer 0-30psi:- Similar to the compensated versions, these devices differ only in null and full scale outputs. Null exhibits a

Hi Suraj, Thanks for the reply. I already have all the associated circuitry ready to connect the transducer to the relay. The only issue I have is the question above. Can you help? Thanks John

Hi, I've got a quick question and one I'm sure you'll all know........whilst falling about the place laughing!! :) I've got a pressure transducer and an LCD panel meter. The pressure transducer has a + and a - Vout. The LCD display has a + and a - Vin. Both are 12VDC. As I am new to electronics I understand Vin/Vout and +/- but what does it mean if there are two inputs/outputs? Would the above be to measure -/+ pressures and hence the -/+Vin on the LCD. I also want to use the output signal from the transducer to activate a relay...would I just use Vout+? Many thanks in advance John

Hmmmm, Just been thinking and I may have answered my question. Is it just a matter of changing the resistance to alter Vref so that when the transduer is at full scale the voltmeter is only displaying 30 on the LED's? Thanks John

Hi MP, I may have missed the point here, you'll have to excuse me as I'm quite new to electronics but learning......slowly but surely!! I actually think the input will be 0-330mV for a 0-30psi range off the tranducer. The thing is if i set full scale to be 330mV etc the unit will read 99. What I would like it to read is 30. Can you advise on this? Many thanks John

Hi Ante, Thanks again for the info. Ill try switching the contacts on the relay. With regards to the relay chatter this shouldn't cause a problem but is it likely to wear the relay out quickly? I notice the other circuit has a resisitor to prevent this. Can this be done to the circuit I am using? I do need the relay to snap on as soon as the pressure hits the set value and close again when it drops below. Would adding the resistor slow the response time of the relay? Thanks John

Hi, I've had a look at the velleman kit and it appears that the LDR resistance drops and the input goes high on the Opamp which then in turn turns the relay to the off position. As all I want to do is place the transducer in place of the LDR can do this and then do something such as reverse the polarity of the relay so that it switches on? Thanks John

Hi Ante, Heres the specs:- Similar to the compensated versions, these devices differ only in null and full scale outputs. Null exhibits a

Hi Ante, Thanks for the info. You will have to excuse my ignorance but what is necessary to adapt the voltage divider to my transducer? It has a 10v excitation..... http://rswww.com/cgi-bin/bv/browse/Module.jsp?BV_SessionID=@@@@1813726976.1101212709@@@@&BV_EngineID=cccjaddddmiedmdcfngcfkmdgkldfil.0&cacheID=ukie&3278665512=3278665512&stockNo=2166253 Many Thanks John

Hi All, Been looking at the light sensor circuit... http://www.electronics-lab.com/projects/sensors/001/index.html and it looks like it would work for a circuit I am creating. Basically I want to replace the LDR with a 0-100mV 4-pin pressure transducer so that at a set pressure, rather than light level, the relay is activated. I would then replace r7 with a larger POT so that the pressure required to activate the relay could be adjusted. I am so close to working this circuit out I can taste it!! If anyone can advise on the component swap I would be eternally grateful! Cheers John