Hi folks, I know the answer is probably staring me in the face, I have some very basic knowledge - I mean VERY basic! - and as the saying goes this can be dangerous so I guess I've done something really daft - humour me if you must and I can trundle off in shame and not speak about this to anyone but I need to make a latch circuit to power up unlatched and then latch with a high pulse from a 4001 monostable. This is part of an intermittent wiper delay that I am making specifically for an older series II Jag that has a rather complex system on it - I know I can probably buy kits to do this but firstly I don't think they will work properly as it is an unconventional design and I would like to use the original stalk switch to operate it, and secondly it'll be much more fun to make my own! The switch is unusual in that it has a separate park position that reverses the wiper motor and parks the blades lower down on the screen. In normal use the blades do not come to rest in the lower position. The plan is that to switch the intermittent circuit on I will flick the wiper switch into park and then to the single wipe within a predetermined time (set by the 4001 monostable). This will then trigger the latch that I am having trouble with and switch on a relay to work the intermittent circuit.
I've tried using a pnp/npn setup and also a 4001 but neither will stay in the unlatched state. Using transistors I have played around with various biasing configurations and although I can switch from one to another they will not stay in that state when the switch is opened. (I forgot to put the switches on the diagram but I am simply shorting out the emitter/base connections).
Using a 4001 (I've chosen this as I have a few lying about) it powers in the latched state and I have the same problem as with the transistor circuit. The only time I can get it to work properly is if I disconnect the output load altogether (the BC639 and relay).
Anyone have any ideas? I'll try to attach a scan of the two circuits I am using but I read somewhere that they may have to go through a moderator first as I am new here.
I've tried using a pnp/npn setup and also a 4001 but neither will stay in the unlatched state. Using transistors I have played around with various biasing configurations and although I can switch from one to another they will not stay in that state when the switch is opened. (I forgot to put the switches on the diagram but I am simply shorting out the emitter/base connections).
Using a 4001 (I've chosen this as I have a few lying about) it powers in the latched state and I have the same problem as with the transistor circuit. The only time I can get it to work properly is if I disconnect the output load altogether (the BC639 and relay).
Anyone have any ideas? I'll try to attach a scan of the two circuits I am using but I read somewhere that they may have to go through a moderator first as I am new here.