Help me?Problem with SPDT Switch

[srikanthnambu]

Hi all

I have problem using the SPDT switches of type DG419 and LA710 Relay .I am doing a project which involves switching of the voltages.The voltages are of type Spike and hold voltage.
The thing is when i am triggering the Switch there is a mismatch between output and input.There is a voltage degradation from +12 spike input to +5V spike output .I think the voltage is being consumed by the switch.WHEN TRIGGERED , I NEED EXACT OUTPUT for any given INPUT .This is my major problem since weeks.
Is there any solution of something like using high power switches or Relays which can sort out the problem.Do anyone have any specification of using such type of switches? Please help me to get rid of this problem.

Regards
Srikanth Nambu

 

[Externet]

...The voltages are of type Spike and hold voltage....

Never heard about those "types" of voltages
You are misinterpreting something in your probing.

 

[smanches]

Are you saying the voltage on input side of the switch is 12v, but the output of the switch is only 5v when it's turned on? Is there anything else in the circuit besides the switch and relay? What are you using for a power supply?

If you are seeing spikes in voltage when you flip the switch on, you will need some snubber capacitors; one at the switch and one at the relay. You might also need a freewheel diode on the relay as well, depending on how much power the coil draws.

 

[KMoffett]

The R(on) for the DG419 is between 20-30Ω. What is the load on the output?

ken

 

[smanches]

OMG, here I had made the assumption this was a mechanical switch.

At 20-30Ω, it's definitely going to drop the voltage significantly.

 

[Roff]

Hi all

I have problem using the SPDT switches of type DG419 and LA710 Relay .I am doing a project which involves switching of the voltages.The voltages are of type Spike and hold voltage.
The thing is when i am triggering the Switch there is a mismatch between output and input.There is a voltage degradation from +12 spike input to +5V spike output .I think the voltage is being consumed by the switch.WHEN TRIGGERED , I NEED EXACT OUTPUT for any given INPUT .This is my major problem since weeks.
Is there any solution of something like using high power switches or Relays which can sort out the problem.Do anyone have any specification of using such type of switches? Please help me to get rid of this problem.

Regards
Srikanth Nambu

Post your schematic.

 

[srikanthnambu]

Hi all....Thanks for reply

1) I have a 6 terminal Spike and hold circuit which generates two voltages i.e., a spike from terminal 6 and hold voltage from terminal 5.

2) The Difference of them would give me Spike and hold voltage i.e., a spike voltage of +12V for 0.5ms and a Hold voltage of +2.3 V for 9.5ms.The total time period is 10ms.This is what i get from the S&H circuit.

3) Now this Voltage is very important to Open and Close the precision VALVES(these LEE precision Valves) that i am using in my project.I have 30 of such Valves.

4) I am using Switches to avoid complexity of the circuit.

5) I need Both Spike and Hold Voltage to Open the Valve.

6) I considered two SPDT switches and connected two valves to
the switch outputs.
7) When Triggered the two switches ,The spike and Hold Voltage as input to Switches from the S&H circuit are getting degraded at the output of the switches by which the Valves are not getting OPENED. This is the main problem i Have.

8) I am thinking of using the Relays instead of the Switches.Would there be of any help using them?


Waiting for reply?

Regards

Srikanth Nambu

 

[KMoffett]

The "analog" switches that you are using are not intended to as power switches. They are designed for switching things like audio signals. Electromechanical "relays" can't switch in the short millisecond periods you require. I'm not seeing this from your written description, can you post a schematic of how you are wring this up?

Ken

 

[smanches]

You need fast switching solid state relays. Something like this would work...


STMicroelectronics | Part Number Search

Although you could probably find comparable SSRs cheaper. This one is specific to automotive use.